Clinical characteristics.

Oculopharyngeal muscular dystrophy (OPMD) is characterized by ptosis and dysphagia due to selective involvement of the muscles of the eyelids and pharynx, respectively. For the vast majority of individuals with typical OPMD, the mean age of onset of ptosis is usually 48 years and of dysphagia 50 years; in 5%-10% of individuals with severe OPMD, onset of ptosis and dysphagia occur before age 45 years and is associated with lower limb girdle weakness starting around age 60 years. Swallowing difficulties, which determine prognosis, increase the risk for potentially life-threatening aspiration pneumonia and poor nutrition. Other manifestations as the disease progresses can include limitation of upward gaze, tongue atrophy and weakness, chewing difficulties, wet voice, facial muscle weakness, axial muscle weakness, and proximal limb girdle weakness predominantly in lower limbs. Some individuals with severe involvement will eventually need a wheelchair. Neuropsychological tests have shown altered scores in executive functions in some.

Diagnosis/testing.

The diagnosis of OPMD is established in a proband with a suggestive phenotype in whom either of the following genetic findings are identified: a heterozygous GCN trinucleotide repeat expansion of 11 to 18 repeats in the first exon of PABPN1 (~90% of affected individuals) or biallelic GCN trinucleotide repeat expansions that are either compound heterozygous (GCN[11] with a second expanded allele) or homozygous (GCN[11]+[11], GCN[12]+[12], GCN[13]+[13], etc.) (~10% of affected individuals).

Management.

Treatment of manifestations: Treatment for ptosis may include blepharoplasty by either resection of the levator palpebrea aponeurosis or frontal suspension of the eyelids. The initial treatment for dysphagia is dietary modification; surgical intervention for dysphagia should be considered when symptomatic dysphagia has a significant impact on quality of life. Physical and occupational therapy are encouraged; assistive devices may be necessary to prevent falls and assist with walking and mobility. Neuropsychological support as needed.

Surveillance: Routine evaluation of: neuromuscular and oculomotor involvement; dysphagia including nutritional status and diet; respiratory function given the increased risk for both aspiration and nocturnal hypoventilation; and cognitive function including development of psychiatric symptoms.

Genetic counseling.

OPMD is inherited in an autosomal dominant manner. The risk to sibs of a proband depends on the genetic status of the parents of the proband:

• If one parent of a proband is heterozygous for a GCN repeat expansion in PABPN1 (GCN[11_18]+ [10]) and the other parent has two normal alleles (GCN[10]+[10]), the risk to the sibs of inheriting a GCN repeat expansion is 50%.
• If both parents of the proband are heterozygous for a GCN repeat expansion, sibs have a 25% risk of inheriting two GCN repeat expansions and a 50% risk of inheriting one GCN repeat expansion.
• If one parent of the proband has biallelic GCN repeat expansions and the other parent has two normal alleles, all sibs will inherit a GCN repeat expansion.
• If one parent of the proband has biallelic GCN repeat expansions and the other parent is heterozygous for a GCN repeat expansion, sibs of the proband have a 50% risk of inheriting biallelic GCN repeat expansions and 50% risk of inheriting one GCN repeat expansion.

Sibs who inherit either one or two GCN repeat expansions will be affected.

Suggestive Findings

Oculopharyngeal muscular dystrophy (OPMD) should be suspected in individuals with a mean age of 48 years with the following clinical and neuroimaging findings. Younger age at onset (<30 years) is often observed in longer GCN expansion or in individuals who are compound heterozygous or homozygous for the GCN expansion.

Clinical findings

• Ptosis, defined as EITHER a vertical separation of at least one palpebral fissure that measures less than 8 mm at rest OR previous corrective surgery for ptosis
• Dysphagia, defined as an increased swallowing time (i.e., >7 seconds when drinking 80 mL of ice-cold water) [Tabor et al 2018, Waito et al 2018].

Note: Proximal muscle weakness (particularly involving pelvic girdle and scapular girdle) may appear later, usually five to ten years after the onset of ptosis.

Whole-body muscle MRI. Fatty involvement of the tongue, soleus, and adductor muscles is very suggestive of OPMD [Alonso-Jimenez et al 2019].

Establishing the Diagnosis

The diagnosis of OPMD is established in a proband with suggestive findings and one of the following identified by molecular genetic testing (see Table 1) [Jouan et al 2014, Richard et al 2015, Richard et al 2017]:

• A heterozygous GCN trinucleotide repeat expansion of 11 to 18 repeats in the first exon of PABPN1 (~90% of affected individuals)
• Biallelic GCN trinucleotide repeat expansions that are either compound heterozygous (GCN[11] with a second expanded allele) or homozygous (GCN[11]+[11], GCN[12]+[12], or GCN[13]+[13]) (~10% of affected individuals)
  Note: Penetrance of an expanded allele depends on both size and zygosity.

Allele sizes. The N in GCN represents any nucleotide (A/C/G/T). All four possible sequences have been observed in the PABPN1 complex repeat.

• Normal alleles have ten GCN repeats: GCN[10].
• Expanded alleles have 11 to 18 GCN repeats: GCN[11_18].

Molecular genetic testing approaches can include a combination of gene-targeted testing (single gene testing, i.e., either sequence analysis of PABPN1 or targeted analysis for PABPN1 GCN trinucleotide repeats in exon 1, or a multigene panel) and comprehensive genomic testing (exome sequencing and genome sequencing).

Gene-targeted testing requires that the clinician determine which gene is likely involved, whereas comprehensive genomic testing does not. Individuals with the distinctive findings described in Suggestive Findings are likely to be diagnosed using gene-targeted testing (see Option 1), whereas those in whom the diagnosis of OPMD has not been considered are more likely to be diagnosed using comprehensive genomic testing (see Option 2).

Clinical Description

Oculopharyngeal muscular dystrophy (OPMD) is characterized by ptosis and dysphagia due to selective involvement of the muscles of the eyelids and pharynx, respectively. Early manifestations of dysphagia include increased time needed to consume a meal and an acquired avoidance of dry foods. The severity of dysphagia is the major determinant of prognosis, as it leads to potentially life-threatening aspiration pneumonia and poor nutrition. Other manifestations, observed as the disease progresses, are limitation of upward gaze, tongue atrophy and weakness, chewing difficulties, wet voice, facial muscle weakness, axial muscle weakness, proximal limb girdle weakness predominantly in lower limbs, and proximal upper extremity weakness (Table 2). Moreover, neuropsychological tests have shown altered scores in executive function compared to controls, which appears to correlate with the larger expansions of PABPN1 [Dubbioso et al 2012] (see also Genotype-Phenotype Correlations).

In typical OPMD (i.e., 90%-95% of affected individuals), the mean age of onset of ptosis is usually 48 years and dysphagia 50 years. The mean age of onset of lower proximal weakness is 58 years [Brisson et al 2020]. In 333 individuals with a heterozygous (GCN)13 expansion, the median latency before the onset of proximal weakness was seven years (range 0-21 years) after the onset of ptosis and seven years (0-25 years) after the onset of dysphagia [Brisson et al 2020].

Severe OPMD (5%-10% of affected individuals) is characterized by onset of ptosis and dysphagia before age 45 years and incapacitating proximal leg weakness that starts before age 60 years. Some individuals with severe involvement eventually need a wheelchair. See also Table 3.

Although OPMD does not appear to reduce life span, in individuals with heterozygous GCN repeat expansions, quality of life in later years is greatly diminished [Becher et al 2001]. In a report of 333 individuals with the (GCN)13 expansion, the main cause of death was respiratory disease [Brisson et al 2020].

Ptosis is always bilateral, but may be asymmetric, at least in the early stage of disease [Brais 2003]. Individuals with severe bilateral ptosis may compensate for visual field limitation with the "astrologist’s posture" – retroflexion of the neck and downward gaze combined with contraction of the frontalis muscles [Rüegg et al 2005].

Extraocular muscles may become gradually affected but complete external ophthalmoplegia is rare [Tomé & Fardeau 1994].

Dropped head beginning at age 67 years and associated with dysphagia, hypernasal speech, ptosis, and proximal limb weakness was reported in a woman who was homozygous for the (GCN)11 expansion [Garibaldi et al 2015].

Dysphagia is detected first for solids and later also for liquids. The degenerative dystrophy and progressive onset of fibrosis of the pharyngeal muscles create difficulties in propelling the food bolus in the pharynx. This, together with a decreased relaxation of the cricopharyngeal muscle (the main muscle of the upper esophageal sphincter [UES] located between the pharynx and the esophagus) results in delay of the transfer of the bolus through the UES.

Of note, while in the past dysphagia resulted in poor nutrition usually causing death by starvation, recent progress (especially in the treatment of pharyngeal dysfunction) has improved the quality of life for persons with OPMD.

Chewing and speaking are also frequently affected [Kroon et al 2020].

Limb muscle involvement is symmetric and mainly concerns the pelvic and scapular girdle. Fatty degeneration of the muscles involves the soleus muscles, the hip adductors, and the hamstrings, especially at the onset the semi-membranous and biceps femoralis muscles.

At later stages, the fatty degeneration spreads to the vastus medialis and intermediate muscles, the gastrocnemius, and the peroneus muscles. The sartorius, gracilis, and tibialis muscles are usually conserved for a longer time [Fischmann et al 2011, Gloor et al 2011]. In the upper limbs, the serratus anterior, latissimus dorsi, and subscapularis muscles are the most affected.

MRI studies also show fatty infiltration of the paraspinal muscles in 76% of affected individuals [Alonso-Jimenez et al 2019].

Distal muscle weakness has been described in a Japanese family [Goto et al 1977, Satoyoshi & Kinoshita 1977] and in other ethnic groups [Jaspar et al 1977, Scrimgeour & Mastaglia 1984]. However, distal muscle involvement at onset has not been associated with typical OPMD [Schotland & Rowland 1964, Vita et al 1983]. In some severe forms, whole-body muscle MRI has shown distal involvement of the lower limbs in the late stages of disease [Alonso-Jimenez et al 2019].

Pain and fatigue. A questionnaire-based study of fatigue, pain, and functional impairment in 35 individuals with genetically confirmed OPMD showed that 54% experienced severe fatigue and pain leading to difficulties with daily living activities and social participation [van der Sluijs et al 2016]. These findings were confirmed in 333 individuals with the (GCN)13 expansion [Brisson et al 2020].

Cognitive impairment. Some individuals have also shown central nervous system involvement [Linoli et al 1991]. Dubbioso et al [2012] described an individual with central nervous system involvement with impaired executive function. Ten persons, with homozygous PAPBN1 (GCN)13-(GCN)13 expansions had cognitive decline, depression, and psychotic manifestations [Blumen et al 2009].

Other clinical findings

• Reduction in FEV1 (forced expiratory volume in one second) ranging from 23% to 59% of the expected values was observed in 13 individuals with OPMD, none of whom required noninvasive ventilation [Witting et al 2014].
• Sleep apnea, reported rarely, is probably underestimated [Dedrick & Brown 2004].
• Cardiomyopathy or rhythm abnormalities have not been associated with OPMD.
• Although OPMD is considered a primary muscle disorder, there are rare reports of findings suggestive of peripheral nerve involvement including severe depletion of myelinated fibers in endomysial nerve twigs of extraocular, pharyngeal, and lingual muscles [Probst et al 1982, Schober et al 2001] and reports of axonal sensorimotor neuropathies in some affected individuals.

Other laboratory findings

• Electromyography (EMG) usually reveals a myopathic pattern especially in weak muscles [Bouchard et al 1997].
• Serum CK concentrations elevated two to seven times above the normal value have been reported in individuals with OPMD with severe leg weakness [Barbeau 1996]; however, serum CK concentration is usually normal or up to twice the upper limit of normal [Richard et al 2017].

Genotype-Phenotype Correlations

Variability of age of onset and severity of weakness correlates with GCN repeat size [Brais et al 1998, Richard et al 2017] (see Table 3). The following generalizations can be made:

• In persons with heterozygous repeats, longer repeat length is associated with earlier age of onset.
• In persons with two expanded alleles (either homozygous or compound heterozygous) age of onset is earlier than in individuals with a single (heterozygous) expanded allele.
• The most severe disease is associated two expanded alleles.

Penetrance

Decade-specific cumulative penetrance for individuals with a heterozygous GCN[13] pathogenic variant is [Brais et al 1997, Richard et al 2017]:

• Age <40 years. 1%
• Age 40-49 years. 6%
• Age 50-59 years. 31%
• Age 60-69 years. 63%
• Age >69 years. 99%

Thus, OPMD resulting from GCN[13] heterozygosity is fully penetrant after age 70 years.

Anticipation

Anticipation is not observed. The PABPN1 GCN repeat is mitotically and meiotically stable: expansion or contraction of the repeat in meiosis is rare. The estimated mutation (expansion/contraction) rate for a heterozygous ([GCN12_17]) allele is approximately 1:500 meiosis [Brais et al 1998].

Nomenclature

Historical numbering of the PABPN1 repeat GCN expansion is described in Molecular Genetics (see PABPN1-specific laboratory technical considerations).

Prevalence

The prevalence of OPMD has been estimated at 1:100,000 in France, 1:1000 in the French-Canadian population of the province of Quebec, and 1:600 among Bukhara Jews living in Israel [Brais et al 1995, Blumen et al 1997, Brunet et al 1997]. A few French-Canadians and members of the genetically isolated population of Bukhara Jews living in Israel [Blumen et al 1999] are homozygous for the expanded alleles GCN[13].

In the United States, the majority of affected individuals are of French-Canadian extraction, though a large number are also of other backgrounds, including Ashkenazi Jewish [Victor et al 1962], and Spanish American in Texas [Becher et al 2001] and California [Grewal et al 1999].

OPMD has been identified in individuals from more than 30 countries.

The frequency of GCN[11] alleles is 1% to 2% of North American, European, and Japanese populations.

Evaluations Following Initial Diagnosis

To establish the extent of disease and needs of an individual diagnosed with oculopharyngeal muscular dystrophy (OPMD), the evaluations summarized in Table 5 (if not performed as part of the evaluation that led to the diagnosis) are recommended.

Treatment of Manifestations

Ptosis. Surgery is recommended when ptosis interferes with vision or appears to cause cervical pain secondary to constant dorsiflexion of the neck. The two types of blepharoplasty used to correct the ptosis are resection of the levator palpebrae aponeurosis and frontal suspension of the eyelids [Codère 1993].

• Resection of the aponeurosis is easily done, but usually needs to be repeated once or twice [Rodrigue & Molgat 1997].
• Frontal suspension of the eyelids uses a thread of muscle fascia as a sling; the fascia is inserted through the tarsal plate of the upper eyelid and the ends are attached in the frontalis muscle, which is relatively preserved in OPMD [Codère 1993]. The major advantage of frontal suspension of the eyelids is that it is permanent; however, the procedure requires general anesthesia.

Dysphagia

• Food should be cut into small pieces.
• Although no controlled trials have been performed [Hill et al 2004], surgical intervention for dysphagia should be considered when symptomatic dysphagia has a significant impact on quality of life [Duranceau et al 1983, St Guily et al 1995, Périé et al 1997, Coiffier et al 2006].
• Cricopharyngeal myotomy, consisting of extramucosal section of the cricopharyngeal muscle that improves swallowing through the upper esophageal sphincter [Montgomery & Lynch 1971, Duranceau et al 1980, St Guily et al 1994, St Guily et al 1995, Duranceau 1997, Gómez-Torres et al 2012], is easily performed through open approach and immediately improves symptoms in most cases [Duranceau et al 1983]; however, in a high proportion of patients progressive dysphagia may recur within a few years [Coiffier et al 2006]. An endoscopic approach may be an alternative approach to open surgery in cricopharyngeal myotomy, with better results than botox injection [Schneider et al 1994, Restivo et al 2000].
• Cricopharyngeal dilation is an alternative to cricopharyngeal myotomy [Mathieu et al 1997]. Repeated cricopharyngeal dilation is a safe, effective, well-tolerated, and long-lasting treatment for dysphagia in OPMD [Manjaly et al 2012].
• In social settings involving food consumption, affected individuals should either avoid eating or choose foods that are easy to swallow.

Limb muscle weakness. Physiotherapy and occupational therapy is encouraged in patients; Canes and walkers may be necessary in patients with walking difficulties to avoid falls. Severe forms of OPMD with advanced stages of lower limb weakness may require a wheelchair [Brisson et al 2020].

Cognitive impairment. A systematic neuropsychological evaluation may be proposed to patients with OPMD and is needed to obtain a better understanding of this issue. A multicentric neuropsychological and psychological evaluation may be considered.

Other. The major complications of OPMD are aspiration pneumonia, weight loss, and social withdrawal because of frequent choking while eating. To reduce the risk of these complications:

• Annual flu vaccination is recommended for elderly affected individuals;
• Consultation should be sought promptly for a productive cough because of the increased risk for lung abscesses;
• Dietary supplements should be added if weight loss is significant.

General anesthesia is not contraindicated, although individuals with OPMD may respond differently to certain anesthetics [Caron et al 2005].

Surveillance

Evaluation of Relatives at Risk

See Genetic Counseling for issues related to testing of at-risk relatives for genetic counseling purposes.

Therapies Under Investigation

Several therapeutic strategies, developed and tested in OPMD models (mammalian cells, nematode, drosophila, mouse) are currently under investigation [Harish et al 2015]. The majority of them are pharmacologic approaches to reduce cell toxicity [Wang et al 2005, Abu-Baker et al 2013, Abu-Baker et al 2018] and/or reduce PABPN1 aggregation. Indeed, reducing PABPN1 aggregation (with drugs such as doxycycline or trehalose) with intrabodies or chaperone expression consistently enhanced cell survival in cell models of OPMD [Bao et al 2002, Bao et al 2004, Abu-Baker et al 2005, Verheesen et al 2006] and improved muscle weakness in both mouse and Drosophila OPMD models [Davies et al 2005, Davies et al 2006, Chartier et al 2009, Barbezier et al 2011, Malerba et al 2019b]. These studies suggest that therapeutic trials in persons with OPMD are possible given that some of the tested molecules have already been given to humans.

Gene replacement strategies (knockdown of mutated PABPN1 and replacement with a functional PABPN1) have also been developed and tested in OPMD models using AAV vectors [Malerba et al 2017, Malerba et al 2019a] or RNA (hammerhead ribozymes/miRNA) [Abu-Baker et al 2019]. Benitec BioPharma received the orphan drug designation for the AAV-based gene therapy product and is now conducting preclinical studies with the aim of a future clinical trial.

A few clinical trials on therapeutic strategies have already been performed on OPMD:

• An autologous cell transplantation clinical Phase I/IIa study (NCT00773227) has been conducted with safety and cell-dose efficacy results [Périé et al 2014]. Twelve individuals were initially included and published; 16 were subsequently added; their results have not yet been published.
• Trehalose has now been tested in a clinical setting in persons with OPMD (Bioblast Biopharma; HOPEMD; NCT02015481) with improvement in dysphagia and muscle function; the effect on the intranuclear inclusions observed in muscle biopsy have not yet been reported [Argov et al 2016].

Search ClinicalTrials.gov in the US and EU Clinical Trials Register in Europe for access to information on clinical studies for a wide range of diseases and conditions.

Mode of Inheritance

Oculopharyngeal muscular dystrophy (OPMD) is inherited in an autosomal dominant manner. The risk to family members depends on whether OPMD in the family is caused by a heterozygous PABPN1 GCN trinucleotide repeat expansion of 11 to 18 repeats or by biallelic PABPN1 GCN repeat expansions.

Risk to Family Members – Proband with a Heterozygous GCN Repeat Expansion

Parents of a proband

• Most individuals with a heterozygous GCN repeat expansion in PABPN1 have an affected parent.
• Molecular genetic testing is recommended for the parents of a proband, regardless of family history, in order to confirm their genetic status and to allow reliable recurrence risk counseling.
  Note: A parent who is heterozygous for the GCN[11] repeat expansion may have been previously unrecognized, presenting only mild OPMD. See Table 3.
• If the GCN repeat expansion identified in the proband is not identified in either parent, the following possibilities should be considered:
  • The proband has a de novo GCN repeat expansion. Note: A pathogenic variant is reported as "de novo" if: (1) the pathogenic variant found in the proband is not detected in parental DNA; and (2) parental identity testing has confirmed biological maternity and paternity. If parental identity testing is not performed, the variant is reported as "assumed de novo" [Richards et al 2015].
  • The proband inherited a GCN repeat expansions from a parent with germline (or somatic and germline) mosaicism. Note: Testing of parental leukocyte DNA may not detect all instances of somatic mosaicism.
• Although most individuals with a heterozygous GCN repeat expansion have an affected parent, the family history may appear to be negative because of failure to recognize the disorder in family members, early death of the parent before the onset of symptoms, or late onset of the disease in the affected parent. Therefore, an apparently negative family history cannot be confirmed unless molecular genetic testing has demonstrated that neither parent has a GCN repeat expansion.

Sibs of a proband. The risk to the sibs of a proband depends on the genetic status of the proband’s parents:

• If one parent of the proband is heterozygous for a GCN repeat expansion and the other parent has two normal (GCN[10]) alleles, the risk to the sibs of inheriting a GCN repeat expansion is 50%.
• If both parents of the proband are heterozygous for a GCN repeat expansion, sibs have a 25% risk of inheriting two GCN repeat expansions and a 50% risk of inheriting one GCN repeat expansion.
• If one parent of the proband has biallelic GCN repeat expansions and the other parent has two normal alleles, all sibs will inherit a GCN repeat expansion.
• Sibs who inherit either one or two GCN repeat expansions will be affected. Age of onset and severity of weakness correlate with GCN repeat length and zygosity (i.e., dosage of GCN repeat expansions). See Genotype-Phenotype Correlations and Penetrance.
• If the GCN repeat expansion identified in the proband cannot be detected in the leukocyte DNA of either parent, the recurrence risk to sibs is estimated to be 1% because of the theoretic possibility of parental germline mosaicism [Rahbari et al 2016].
• If the parents have not been tested for the GCN repeat expansion identified in the proband but are clinically unaffected, sibs are still presumed to be at increased risk for OPMD because of the possibility of late onset in a heterozygous parent or the theoretic possibility of parental germline mosaicism.

Offspring of a proband

• Unless an individual who is heterozygous for a GCN repeat expansion has children with an individual who has heterozygous or biallelic GCN repeat expansions, the individual's offspring have a 50% chance of inheriting the GCN repeat expansion.
• The likelihood that the reproductive partner of a proband also has heterozygous or biallelic GCN repeat expansions is higher in individuals of French-Canadian extraction and in Bukhara Jews living in Israel (see Prevalence).

Other family members. The risk to other family members depends on the genetic status of the proband's parents: if a parent has a heterozygous GCN repeat expansion, the parent's family members may be at risk.

Risk to Family Members – Proband with Biallelic GCN Repeat Expansions

Parents of a proband

• Both parents of an individual with biallelic GCN repeat expansions are typically heterozygous for a GCN repeat expansion. In rare instances, one parent is heterozygous and the other parent has biallelic GCN repeat expansions.
• The parents of an individual with biallelic GCN repeat expansions may or may not have manifestations of OPMD depending on the length of their respective GCN repeat expansions. Note: A parent who is heterozygous for the GCN[11] repeat expansion may have been previously unrecognized, presenting only mild OPMD (see Table 3 and Penetrance).
• Molecular genetic testing is recommended for the parents of a proband to confirm the genetic status of each parent and to allow reliable recurrence risk assessment.

Sibs of a proband

• If both parents of the proband are heterozygous for a GCN repeat expansion, sibs of the proband have a 25% risk of inheriting two GCN repeat expansions and a 50% risk of inheriting one GCN repeat expansion.
• If one parent of the proband has biallelic GCN repeat expansions and the other parent is heterozygous for a GCN repeat expansion, sibs of the proband have a 50% risk of inheriting biallelic GCN repeat expansions and 50% risk of inheriting one GCN repeat expansion.
• Sibs of the proband who inherit either one or two GCN repeat expansions will be affected. Age of onset and severity of weakness correlate with GCN repeat length and zygosity (i.e., dosage of GCN repeat expansions). See Table 3 and Penetrance.

Offspring of a proband. Unless an individual with biallelic GCN repeat expansions has children with an individual who has heterozygous or biallelic GCN repeat expansions, the individual's offspring will be heterozygous for a GCN repeat expansion.

Other family members. The risk to other family members depends on the genetic status of the proband's parents: if a parent of the proband has a GCN repeat expansion, the parent's family members may be at risk.

Related Genetic Counseling Issues

Family planning

• The optimal time for determination of genetic risk and discussion of the availability of prenatal/preimplantation genetic testing is before pregnancy.
• It is appropriate to offer genetic counseling (including discussion of potential risks to offspring and reproductive options) to young adults who are affected or at risk.

Predictive testing (i.e., testing of asymptomatic at-risk individuals)

• Predictive testing for at-risk relatives is possible once the GCN repeat expansion(s) have been identified in an affected family member.
• Potential consequences of such testing (including, but not limited to, socioeconomic changes and the need for long-term follow up and evaluation arrangements for individuals with a positive test result) as well as the capabilities and limitations of predictive testing should be discussed in the context of formal genetic counseling prior to testing.

Predictive testing in minors (i.e., testing of asymptomatic at-risk individuals younger than age 18 years)

• For asymptomatic minors at risk for adult-onset conditions for which early treatment would have no beneficial effect on disease morbidity and mortality, predictive genetic testing is considered inappropriate, primarily because it negates the autonomy of the child with no compelling benefit. Further, concern exists regarding the potential unhealthy adverse effects that such information may have on family dynamics, the risk of discrimination and stigmatization in the future, and the anxiety that such information may cause.
• For more information, see the National Society of Genetic Counselors position statement on genetic testing of minors for adult-onset conditions and the American Academy of Pediatrics and American College of Medical Genetics and Genomics policy statement: ethical and policy issues in genetic testing and screening of children.

In a family with an established diagnosis of OPMD, it is appropriate to consider testing of symptomatic individuals regardless of age.

Prenatal Testing and Preimplantation Genetic Testing

Differences in perspective may exist among medical professionals and within families regarding the use of prenatal testing and preimplantation genetic testing. The National Society of Genetic Counselors (NSGC) does not recommend prenatal genetic testing for known adult-onset conditions if pregnancy or childhood management will not be affected. Due to potential medical and ethical complexities, NSGC recommends that prior to undergoing testing, prospective parents meet with a genetic counselor or other healthcare specialists with genetics expertise to discuss the implications of prenatal testing for adult-onset conditions. Pre-test counseling should include a discussion of the natural history of the condition, availability of treatments or interventions, concerns that prenatal testing for adult-onset conditions may deny a child’s future autonomy, and potential for genetic discrimination.

Molecular Pathogenesis

PABPN1 encodes PABPN1, an abundant nuclear protein that shuttles between nucleus and cytoplasm [Calado et al 2000]. PABPN1 associates with RNA polymerase II during transcription; binding to the poly(A) RNAs, it accompanies the released transcripts through the nuclear pore [Bear et al 2003, Kerwitz et al 2003].

PABPN1 is ubiquitously expressed at a very low level in skeletal muscle [Apponi et al 2010] and is mostly localized in the nucleus with enrichment in nuclear speckles (the pre-mRNA processing subnuclear area) [Banerjee et al 2013]. PABPN1 specifically binds the poly(A) sequences of mRNAs and is implicated in mRNA polyadenylation activity.

Other roles of PABPN1:

• Splicing regulation [Bergeron et al 2015]
• Nuclear surveillance via hyperadenylation and decay of RNA [Bresson & Conrad 2013]
• Regulation of noncoding RNA (lncRNA) [Beaulieu et al 2012]
• Regulation of small nucleolar RNA (snoRNA) processing [Lemay et al 2010]
• Regulation of nuclear-encoded mitochondrial RNA [Chartier et al 2015, Vest et al 2017]

PABPN1 nuclear aggregates are a pathologic hallmark of the disease; aggregates are found in 5%-15% of myofiber nuclei in affected and unaffected muscle sections of persons with OPMD [Tomé & Fardeau 1980, Tomé et al 1997, Calado et al 2000, Gidaro et al 2013]. PABPN1 depletion leads to abnormal organization of the nuclear speckle and alteration of RNA editing (adenosine to inosine) [Banerjee et al 2017].

Mechanism of disease causation. OPMD pathogenesis likely occurs through a polyalanine toxicity gain-of-function mechanism, such as abnormal aggregation and inefficient protein degradation [Brais et al 1998, Brais et al 1999, Banerjee et al 2013]. Inclusion formation and PABPN1 inclusions have a broad and significant effect on the expression of genes involved in mRNA processing [Corbeil-Girard et al 2005] and on RNA splicing [Klein et al 2016].

Another emerging hypothesis in OPMD is a PABPN1 loss of function in cells, either directly via mutation of PABPN1 or indirectly via PABPN1 sequestration in aggregates [Banerjee et al 2013, Vest et al 2017].

PABPN1-specific laboratory technical considerations. The PABPN1 repeat causing OPMD is designated GCN, where N represents any A/C/G/T nucleotide, due to normal variation in the sequence. All four possible codons encode alanine. Of note, both Sanger sequencing and next-generation sequencing can be used to determine the repeat size and sequence.

The GCN repeat expansion has been described in various ways. Repeat expansions were first described as pure (GCG) expansions of a (GCG)6 stretch coding for six alanines in the first exon [Brais et al 1998].

• The normal GCN[10] allele was referred to as (GCN)6.
• The pathogenic GCN[11_18] alleles were referred to as (GCN)7-14.

When available, the full sequence of normal and pathogenic (expanded) alleles should be reported; for example, an Ala13 allele may have a sequence of GCG[10]GCA[1]GCG[2] (previously reported as (GCG)10(GCA)1(GCG)2).

A European Neuromuscular Center (ENMC) workshop on OPMD [Raz et al 2013] suggested the following variant nomenclature for the number of PABPN1 triplet repeats / number of alanines:

• Normal allele. (GCN)10 / Ala10 (See Figure 1.)
• Pathogenic alleles. (GCN)11-18 and Ala11-18, where the range of triplet repeats/alanines is 11-18

Figure 1

Upper figure: schematic representation of PABPN1 Lower figure: portion of exon 1 containing the triplet repeat (GCN)10, with the corresponding polyalanine tract in the protein sequence below

The nomenclature of the Human Genome Variation Society (HGVS) for these alleles is given in Table 7.

Author Notes

Alexis Boulinguiez, PhD
Myology Centre for Research UMR974
INSERM, Sorbonne Université
Institut de Myologie, Paris

Gillian Butler-Browne, PhD
Myology Centre for Research UMR974
INSERM, Sorbonne Université
Institut de Myologie, Paris

Teresinha Evangelista, MD
Neuromuscular Morphology Unit
Myology Institute
GHU Pitié-Salpêtrière
Sorbonne Université, Paris

Jean Lacau St Guily, MD
Myology Centre for Research UMR974
INSERM, Sorbonne Université
Institut de Myologie, Paris

Pascale Richard, PharmD, PhD
APHP, Unité Fonctionnelle de Cardiogénétique et Myogénétique Moléculaire
Hôpitaux Universitaires Pitié Salpêtrière-Charles Foix, Paris

Fanny Roth, PhD
Myology Centre for Research UMR974
INSERM, Sorbonne Université
Institut de Myologie, Paris

Tanya Stojkovic, MD
APHP, Centre de Référence des Maladies Neuromusculaire
Institut de Myologie
Hôpitaux Universitaires Pitié Salpêtrière-Charles Foix, Paris

Capucine Trollet, PhD
Myology Centre for Research UMR974
INSERM, Sorbonne Université
Institut de Myologie, Paris

https://www.afm-telethon.fr/fr/fiches-maladies/dystrophie-musculaire-oculopharyngee

recherche-myologie.fr/research/labs/trollet-mouly-lab/?lang=en

www.institut-myologie.org/en

Author History

Alexis Boulinguiez, PhD (2020-present)
Bernard Brais, MD, MPhil, PhD; Hôpital Notre-Dame-CHUM, Montréal (2001-2014)
Gillian Butler-Browne, PhD (2014-present)
Teresinha Evangelista, MD (2020-present)
Teresa Gidaro, MD, PhD; Institut de Myologie, Paris (2014-2020)
Pierre Klein, PhD; Institut de Myologie, Paris (2014-2020)
Jean Lacau St Guily, MD (2014-present)
Sophie Périé, MD, PhD; Université Pierre et Marie Curie, Paris (2014-2020)
Pascale Richard, PharmD, PhD (2020-present)
Fanny Roth, PhD (2020-present)
Guy A Rouleau, MD, PhD; Hôpital Notre-Dame-CHUM, Montreal (2001-2014)
Capucine Trollet, PhD (2014-present)
Tanya Stojkovic, MD (2020-present)

Revision History

• 22 October 2020 (bp) Comprehensive update posted live
• 20 February 2014 (me) Comprehensive update posted live
• 22 June 2006 (ca) Comprehensive update posted live
• 3 December 2003 (me) Comprehensive update posted live
• 8 March 2001 (me) Review posted live
• December 2000 (bb) Original submission

Published Guidelines / Consensus Statements

• Association française contre les myopathies. Zoom sur la Dystrophie Musculaire Oculopharyngée. Evry, France: Monographies Myoline. Available online. 2018. Accessed 4-4-23.
• Committee on Bioethics, Committee on Genetics, and American College of Medical Genetics and Genomics Social, Ethical, Legal Issues Committee. Ethical and policy issues in genetic testing and screening of children. Available online. 2013. Accessed 4-4-23.
• National Society of Genetic Counselors. Position statement on genetic testing of minors for adult-onset conditions. Available online. 2018. Accessed 4-4-23.

Literature Cited

• Abu-Baker A, Kharma N, Perreault J, Grant A, Shekarabi M, Maios C, Dona M, Neri C, Dion PA, Parker A, Varin L, Rouleau GA. RNA-based therapy utilizing oculopharyngeal muscular dystrophy transcript knockdown and replacement. Mol Ther Nucleic Acids. 2019;15:12–25. [PMC free article: PMC6403420] [PubMed: 30831428]
• Abu-Baker A, Laganiere S, Fan X, Laganiere J, Brais B, Rouleau GA. Cytoplasmic targeting of mutant poly(A)-binding protein nuclear 1 suppresses protein aggregation and toxicity in oculopharyngeal muscular dystrophy. Traffic. 2005;6:766–79. [PubMed: 16101680]
• Abu-Baker A, Laganiere J, Gaudet R, Rochefort D, Brais B, Neri C, Dion PA, Rouleau GA. Lithium chloride attenuates cell death in oculopharyngeal muscular dystrophy by perturbing Wnt/β-catenin pathway. Cell Death Dis. 2013;4:e821. [PMC free article: PMC3824652] [PubMed: 24091664]
• Abu-Baker A, Parker A, Ramalingam S, Laganiere J, Brais B, Neri C, Dion P, Rouleau G. Valproic acid is protective in cellular and worm models of oculopharyngeal muscular dystrophy. Neurology. 2018;91:e551–e561. [PMC free article: PMC6105050] [PubMed: 30006409]
• Alonso-Jimenez A, Kroon RHMJM, Alejaldre-Monforte A, Nuñez-Peralta C, Horlings CGC, van Engelen BGM, Olivé M, González L, Verges-Gil E, Paradas C, Márquez C, Garibaldi M, Gallano P, Rodriguez MJ, Gonzalez-Quereda L, Dominguez Gonzalez C, Vissing J, Fornander F, Eisum AV, García-Sobrino T, Pardo J, García-Figueiras R, Muelas N, Vilchez JJ, Kapetanovic S, Tasca G, Monforte M, Ricci E, Gomez MT, Bevilacqua JA, Diaz-Jara J, Zamorano II, Carlier RY, Laforet P, Pelayo-Negro A, Ramos-Fransi A, Martínez A, Marini-Bettolo C, Straub V, Gutiérrez G, Stojkovic T, Martín MA, Morís G, Fernández-Torrón R, Lopez De Munaín A, Cortes-Vicente E, Querol L, Rojas-García R, Illa I, Diaz-Manera J. Muscle MRI in a large cohort of patients with oculopharyngeal muscular dystrophy. J Neurol Neurosurg Psychiatry. 2019;90:576–85. [PubMed: 30530568]
• Apponi LH, Leung SW, Williams KR, Valentini SR, Corbett AH, Pavlath GK. Loss of nuclear poly(A)-binding protein 1 causes defects in myogenesis and mRNA biogenesis. Hum Mol Genet. 2010;19:1058–65. [PMC free article: PMC2830829] [PubMed: 20035013]
• Argov Z, Gliko-Kabir I, Brais B, Caraco Y, Megiddo D. Intravenous trehalose improves dysphagia and muscle function in oculopharyngeal muscular dystrophy (OPMD): preliminary results of 24 weeks open label Phase 2 trial (S28.004). Neurology. 2016:86.
• Askanas V, Engel WK. New advances in the understanding of sporadic inclusion-body myositis and hereditary inclusion-body myopathies. Curr Opin Rheumatol. 1995;7:486–96. [PubMed: 8579968]
• Audag N, Goubau C, Toussaint M, Reychler G. Screening and evaluation tools of dysphagia in adults with neuromuscular diseases: a systematic review. Ther Adv Chronic Dis. 2019;10:2040622318821622. [PMC free article: PMC6357297] [PubMed: 30728931]
• Banerjee A, Apponi LH, Pavlath GK, Corbett AH. PABPN1: molecular function and muscle disease. FEBS J. 2013;280:4230–50. [PMC free article: PMC3786098] [PubMed: 23601051]
• Banerjee A, Vest KE, Pavlath GK, Corbett AH. Nuclear poly(A) binding protein 1 (PABPN1) and Matrin3 interact in muscle cells and regulate RNA processing. Nucleic Acids Res. 2017;45:10706–25. [PMC free article: PMC5737383] [PubMed: 28977530]
• Bao YP, Cook LJ, O'Donovan D, Uyama E, Rubinsztein DC. Mammalian, yeast, bacterial, and chemical chaperones reduce aggregate formation and death in a cell model of oculopharyngeal muscular dystrophy. J Biol Chem. 2002;277:12263–9. [PubMed: 11796717]
• Bao YP, Sarkar S, Uyama E, Rubinsztein DC. Congo red, doxycycline, and HSP70 overexpression reduce aggregate formation and cell death in cell models of oculopharyngeal muscular dystrophy. J Med Genet. 2004;41:47–51. [PMC free article: PMC1757258] [PubMed: 14729833]
• Barbeau A. The syndrome of hereditary late-onset ptosis and dysphagia in French Canada. In: Kühn E, ed. Symposium über Progressive Muskeldystrophie. Berlin, Germany: Springer-Verlag; 1996:102-9.
• Barbezier N, Chartier A, Bidet Y, Buttstedt A, Voisset C, Galons H, Blondel M, Schwarz E, Simonelig M. Antiprion drugs 6-aminophenanthridine and guanabenz reduce PABPN1 toxicity and aggregation in oculopharyngeal muscular dystrophy. EMBO Mol Med. 2011;3:35–49. [PMC free article: PMC3044817] [PubMed: 21204267]
• Bear DG, Fomproix N, Soop T, Bjorkroth B, Masich S, Daneholt B. Nuclear poly(A)-binding protein PABPN1 is associated with RNA polymerase II during transcription and accompanies the released transcript to the nuclear pore. Exp Cell Res. 2003;286:332–44. [PubMed: 12749861]
• Beaulieu YB, Kleinman CL, Landry-Voyer AM, Majewski J, Bachand F. Polyadenylation-dependent control of long noncoding RNA expression by the poly(A)-binding protein nuclear 1. PLoS Genet. 2012;8:e1003078. [PMC free article: PMC3499365] [PubMed: 23166521]
• Becher MW, Morrison L, Davis LE, Maki WC, King MK, Bicknell JM, Reinert BL, Bartolo C, Bear DG. Oculopharyngeal muscular dystrophy in Hispanic New Mexicans. JAMA. 2001;286:2437–40. [PubMed: 11712939]
• Bergeron D, Pal G, Beaulieu YB, Chabot B, Bachand F. Regulated intron retention and nuclear pre-mRNA decay contribute to PABPN1 autoregulation. Mol Cell Biol. 2015;35:2503–17. [PMC free article: PMC4475927] [PubMed: 25963658]
• Blumen SC, Bouchard JP, Brais B, Carasso RL, Paleacu D, Drory VE, Chantal S, Blumen N, Braverman I. Cognitive impairment and reduced life span of oculopharyngeal muscular dystrophy homozygotes. Neurology. 2009;73:596–601. [PubMed: 19704078]
• Blumen SC, Brais B, Korczyn AD, Medinsky S, Chapman J, Asherov A, Nisipeanu P, Codère F, Bouchard JP, Fardeau M, Tome FM, Rouleau GA. Homozygotes for oculopharyngeal muscular dystrophy have a severe form of the disease. Ann Neurol. 1999;46:115–8. [PubMed: 10401788]
• Blumen SC, Nisipeanu P, Sadeh M, Asherov A, Blumen N, Wirguin Y, Khilkevich O, Carasso RL, Korczyn AD. Epidemiology and inheritance of oculopharyngeal muscular dystrophy in Israel. Neuromuscul Disord. 1997;7:S38–40. [PubMed: 9392014]
• Bouchard JP, Brais B, Brunet D, Gould PV, Rouleau GA. Recent studies on oculopharyngeal muscular dystrophy in Quebec. Neuromuscul Disord. 1997;7:S22–9. [PubMed: 9392011]
• Bouchard JP, Marcoux S, Gosselin F, Pineault D, Rouleau GA. A simple test for the detection of the dysphagia in members of families with oculopharyngeal muscular dystrophy (OPMD). Can J Neurol Sci. 1992;19:296–7.
• Brais B. Oculopharyngeal muscular dystrophy: a late-onset polyalanine disease. Cytogenet Genome Res. 2003;100:252–60. [PubMed: 14526187]
• Brais B, Bouchard JP, Gosselin F, Xie YG, Fardeau M, Tome FM, Rouleau GA. Using the full power of linkage analysis in 11 French Canadian families to fine map the oculopharyngeal muscular dystrophy gene. Neuromuscul Disord. 1997;7:S70–4. [PubMed: 9392020]
• Brais B, Bouchard JP, Xie YG, Rochefort DL, Chretien N, Tome FM, Lafreniere RG, Rommens JM, Uyama E, Nohira O, Blumen S, Korczyn AD, Heutink P, Mathieu J, Duranceau A, Codère F, Fardeau M, Rouleau GA, Korczyn AD. Short GCG expansions in the PABP2 gene cause oculopharyngeal muscular dystrophy. Nat Genet. 1998;18:164–7. [PubMed: 9462747]
• Brais B, Rouleau GA, Bouchard JP, Fardeau M, Tome FM. Oculopharyngeal muscular dystrophy. Semin Neurol. 1999;19:59–66. [PubMed: 10711989]
• Brais B, Xie YG, Sanson M, Morgan K, Weissenbach J, Korczyn AD, Blumen SC, Fardeau M, Tomé FM, Bouchard JP, Rouleau GA. The oculopharyngeal muscular dystrophy locus maps to the region of the cardiac alpha and beta myosin heavy chain genes on chromosome 14q11.2-q13. Hum Mol Genet. 1995;4:429–34. [PubMed: 7795598]
• Bresson SM, Conrad NK. The human nuclear poly(a)-binding protein promotes RNA hyperadenylation and decay. PLoS Genet. 2013;9:e1003893. [PMC free article: PMC3798265] [PubMed: 24146636]
• Brisson JD, Gagnon C, Brais B, Côté I, Mathieu J. A study of impairments in oculopharyngeal muscular dystrophy. Muscle Nerve. 2020;62:201–7. [PubMed: 32270505]
• Brunet G, Tome FM, Eymard B, Robert JM, Fardeau M. Genealogical study of oculopharyngeal muscular dystrophy in France. Neuromuscul Disord. 1997;7:S34–7. [PubMed: 9392013]
• Calado A, Tome FM, Brais B, Rouleau GA, Kühn U, Wahle E, Carmo-Fonseca M. Nuclear inclusions in oculopharyngeal muscular dystrophy consist of poly(A) binding protein 2 aggregates which sequester poly(A) RNA. Hum Mol Genet. 2000;9:2321–8. [PubMed: 11001936]
• Caron MJ, Girard F, Girard DC, Boudreault D, Brais B, Nassif E, Chouinard P, Ruel M, Duranceau A. Cisatracurium pharmacodynamics in patients with oculopharyngeal muscular dystrophy. Anesth Analg. 2005;100:393–7. [PubMed: 15673864]
• Chartier A, Klein P, Pierson S, Barbezier N, Gidaro T, Casas F, Carberry S, Dowling P, Maynadier L, Bellec M, Oloko M, Jardel C, Moritz B, Dickson G, Mouly V, Ohlendieck K, Butler-Browne G, Trollet C, Simonelig M. Mitochondrial dysfunction reveals the role of mRNA poly(A) tail regulation in oculopharyngeal muscular dystrophy pathogenesis. PloS Genet. 2015;11:e1005092. [PMC free article: PMC4376527] [PubMed: 25816335]
• Chartier A, Raz V, Sterrenburg E, Verrips CT, van der Maarel SM, Simonelig M. Prevention of oculopharyngeal muscular dystrophy by muscular expression of Llama single-chain intrabodies in vivo. Hum Mol Genet. 2009;18:1849–59. [PubMed: 19258344]
• Codère F. Oculopharyngeal muscular dystrophy. Can J Ophthalmol. 1993;28:1–2. [PubMed: 8439856]
• Coiffier L, Périé S, Laforêt P, Eymard B, St Guily JL. Long-term results of cricopharyngeal myotomy in oculopharyngeal muscular dystrophy. Otolaryngol Head Neck Surg. 2006;135:218–22. [PubMed: 16890071]
• Corbeil-Girard LP, Klein AF, Sasseville AM, Lavoie H, Dicaire MJ, Saint-Denis A, Page M, Duranceau A, Codère F, Bouchard JP, Karpati G, Rouleau GA, Massie B, Langelier Y, Brais B. PABPN1 overexpression leads to upregulation of genes encoding nuclear proteins that are sequestered in oculopharyngeal muscular dystrophy nuclear inclusions. Neurobiol Dis. 2005;18:551–67. [PubMed: 15755682]
• Davies JE, Sarkar S, Rubinsztein DC. Trehalose reduces aggregate formation and delays pathology in a transgenic mouse model of oculopharyngeal muscular dystrophy. Hum Mol Genet. 2006;15:23–31. [PubMed: 16311254]
• Davies JE, Wang L, Garcia-Oroz L, Cook LJ, Vacher C, O'Donovan DG, Rubinsztein DC. Doxycycline attenuates and delays toxicity of the oculopharyngeal muscular dystrophy mutation in transgenic mice. Nat Med. 2005;11:672–7. [PubMed: 15864313]
• Dedrick DL, Brown LK. Obstructive sleep apnea syndrome complicating oculopharyngeal muscular dystrophy. Chest. 2004;125:334–6. [PubMed: 14718463]
• Deng J, Yu J, Li P, Luan X, Cao L, Zhao J, Yu M, Zhang W, Lv H, Xie Z, Meng L, Zheng Y, Zhao Y, Gang Q, Wang Q, Liu J, Zhu M, Guo X, Su Y, Liang Y, Liang F, Hayashi T, Maeda MH, Sato T, Ura S, Oya Y, Ogasawara M, Iida A, Nishino I, Zhou C, Yan C, Yuan Y, Hong D, Wang Z. Expansion of GGC repeat in GIPC1 is associated with oculopharyngodistal myopathy. Am J Hum Genet. 2020;106:793–804. [PMC free article: PMC7273532] [PubMed: 32413282]
• Dodds WJ, Logemann JA, Stewart ET. Radiologic assessment of abnormal oral and pharyngeal phases of swallowing. AJR Am J Roentgenol. 1990;154:965–74. [PubMed: 2108570]
• Dubbioso R, Moretta P, Manganelli F, Fiorillo C, Iodice R, Trojano L, Santoro L. Executive functions are impaired in heterozygote patients with oculopharyngeal muscular dystrophy. J Neurol. 2012;259:833–7. [PubMed: 21956377]
• Duranceau A. Cricopharyngeal myotomy in the management of neurogenic and muscular dysphagia. Neuromuscul Disord. 1997;7:S85–9. [PubMed: 9392023]
• Duranceau A, Forand MD, Fauteux JP. Surgery in oculopharyngeal muscular dystrophy. Am J Surg. 1980;139:33–9. [PubMed: 7350844]
• Duranceau AC, Beauchamp G, Jamieson GG, Barbeau A. Oropharyngeal dysphagia and oculopharyngeal muscular dystrophy. Surg Clin North Am. 1983;63:825–32. [PubMed: 6351296]
• Fischmann A, Gloor M, Fasler S, Haas T, Rodoni Wetzel R, Bieri O, et al. Muscular involvement assessed by MRI correlates to motor function measurement values in oculopharyngeal muscular dystrophy. J Neurol. 2011;258:1333–40. [PubMed: 21340522]
• Fukuhara N, Kumamoto T, Tsubaki T. Rimmed vacuoles. Acta Neuropathol. 1980;51:229–35. [PubMed: 7445977]
• Galimberti V, Tironi R, Lerario A, Scali M, Del Bo R, Rodolico C, Brizzi T, Gibertini S, Maggi L, Mora M, Toscano A, Comi GP, Sciacco M, Moggio M, Peverelli L. Value of insoluble PABPN1 accumulation in the diagnosis of oculopharyngeal muscular dystrophy. Eur J Neurol. 2020;27:709–15. [PubMed: 31769567]
• Garibaldi M, Pennisi EM, Bruttini M, Bizzarri V, Bucci E, Morino S, Talerico C, Stoppacciaro A, Renieri A, Antonini G. Dropped-head in recessive oculopharyngeal muscular dystrophy. Neuromuscul Disord. 2015;25:869–72. [PubMed: 26494409]
• Gidaro T, Negroni E, Périé S, Mirabella M, Lainé J, Lacau St Guily J, Butler-Browne G, Mouly V, Trollet C. Atrophy, fibrosis, and increased PAX7-positive cells in pharyngeal muscles of oculopharyngeal muscular dystrophy patients. J Neuropathol Exp Neurol. 2013;72:234–43. [PubMed: 23399899]
• Gloor M, Fasler S, Fischmann A, Haas T, Bieri O, Heinimann K, et al. Quantification of fat infiltration in oculopharyngeal muscular dystrophy: comparison of three MR imaging methods. J Magn Reson Imaging. 2011;33:203–10. [PubMed: 21182140]
• Gómez-Torres A, Abrante Jiménez A, Rivas Infante E, Menoyo Bueno A, Tirado Zamora I, Esteban Ortega F. Cricopharyngeal myotomy in the treatment of oculopharyngeal muscular dystrophy. Acta Otorrinolaringol Esp. 2012;63:465–9. [PubMed: 22898142]
• Goto I, Kanazawa Y, Kobayashi T, Murai Y, Kuroiwa Y. Oculopharyngeal myopathy with distal and cardiomyopathy. J Neurol Neurosurg Psychiatry. 1977;40:600–7. [PMC free article: PMC492768] [PubMed: 903774]
• Goyal NA, Mozaffar T, Chui LA. Oculopharyngeal muscular dystrophy, an often misdiagnosed neuromuscular disorder: a Southern California experience. J Clin Neuromuscul Dis. 2019;21:61–8. [PubMed: 31743248]
• Grewal RP, Karkera JD, Grewal RK, Detera-Wadleigh SD. Mutation analysis of oculopharyngeal muscular dystrophy in Hispanic American families. Arch Neurol. 1999;56:1378–81. [PubMed: 10555658]
• Harish P, Malerba A, Dickson G, Bachtarzi H. Progress on gene therapy, cell therapy, and pharmacological strategies toward the treatment of oculopharyngeal muscular dystrophy. Hum Gene Ther. 2015;26:286–92. [PubMed: 25860803]
• Hill M, Hughes T, Milford C. Treatment for swallowing difficulties (dysphagia) in chronic muscle disease. Cochrane Database Syst Rev. 2004;2:CD004303. [PubMed: 15106246]
• Ishiura H, Shibata S, Yoshimura J, Suzuki Y, Qu W, Doi K, Almansour MA, Kikuchi JK, Taira M, Mitsui J, Takahashi Y, Ichikawa Y, et al. Noncoding CGG repeat expansions in neuronal intranuclear inclusion disease, oculopharyngodistal myopathy and an overlapping disease. Nature Genet. 2019;51:1222–32. [PubMed: 31332380]
• Jaspar HH, Bastiaensen LA, ter Laak HJ, Joosten EM, Horstink MW, Stadhouders AM. Oculopharyngodistal myopathy with early onset and neurogenic features. Clin Neurol Neurosurg. 1977;80:272–82. [PubMed: 216518]
• Jouan L, Rocheford D, Szuto A, Carney E, David K, Dion PA, Rouleau GA. An 18 alanine repeat in a severe form of oculopharyngeal muscular dystrophy. Can J Neurol Sci. 2014;41:508–11. [PubMed: 24878479]
• Kerwitz Y, Kühn U, Lilie H, Knoth A, Scheuermann T, Friedrich H, Schwarz E, Wahle E. Stimulation of poly(A) polymerase through a direct interaction with the nuclear poly(A) binding protein allosterically regulated by RNA. EMBO J. 2003;22:3705–14. [PMC free article: PMC165617] [PubMed: 12853485]
• Klein P, Oloko M, Roth F, Montel V, Malerba A, Jarmin S, Gidaro T, Popplewell L, Perie S, Lacau St Guily J, de la Grange P, Antoniou MN, Dickson G, Butler-Browne G, Bastide B, Mouly V, Trollet C. Nuclear poly(A)-binding protein aggregates misplace a pre-mRNA outside of SC35 speckle causing its abnormal splicing. Nucleic Acids Res. 2016;44:10929–45. [PMC free article: PMC5159528] [PubMed: 27507886]
• Kroon RHMJM, Horlings CGC, de Swart BJM, van Engelen BGM, Kalf JG. Swallowing, chewing and speaking: frequently impaired in oculopharyngeal muscular dystrophy. J Neuromuscul Dis. 2020;7:483–94. [PMC free article: PMC7592669] [PubMed: 32804098]
• Langmore SE, Schatz K, Olson N. Endoscopic and videofluoroscopic evaluations of swallowing and aspiration. Ann Otol Rhinol Laryngol. 1991;100:678–81. [PubMed: 1872520]
• Leclerc A, Tomé FM, Fardeau M. Ubiquitin and beta-amyloid-protein in inclusion body myositis (IBM), familial IBM-like disorder and oculopharyngeal muscular dystrophy: an immunocytochemical study. Neuromuscul Disord. 1993;3:283–91. [PubMed: 8268725]
• Lemay JF, D'Amours A, Lemieux C, Lackner DH, St-Sauveur VG, Bähler J, Bachand F. The nuclear poly(A)-binding protein interacts with the exosome to promote synthesis of noncoding small nucleolar RNAs. Mol Cell. 2010;37:34–45. [PubMed: 20129053]
• Linoli G, Tomelleri G, Ghezzi M. Oculopharyngeal muscular dystrophy. Description of a case with involvement of the central nervous system. Pathologica. 1991;83:325–34. [PubMed: 1923632]
• Malerba A, Klein P, Bachtarzi H, Jarmin SA, Cordova G, Ferry A, Strings V, Espinoza MP, Mamchaoui K, Blumen SC, St Guily JL, Mouly V, Graham M, Butler-Browne G, Suhy DA, Trollet C, Dickson G. PABPN1 gene therapy for oculopharyngeal muscular dystrophy. Nat Commun. 2017;8:14848. [PMC free article: PMC5380963] [PubMed: 28361972]
• Malerba A, Klein P, Lu-Nguyen N, Cappellari O, Strings-Ufombah V, Harbaran S, Roelvink P, Suhy D, Trollet C, Dickson G. Established PABPN1 intranuclear inclusions in OPMD muscle can be efficiently reversed by AAV-mediated knockdown and replacement of mutant expanded PABPN1. Hum Mol Genet. 2019a;28:3301–8. [PMC free article: PMC7343048] [PubMed: 31294444]
• Malerba A, Roth F, Harish P, Dhiab J, Lu-Nguyen N, Cappellari O, Jarmin S, Mahoudeau A, Ythier V, Lainé J, Negroni E, Abgueguen E, Simonelig M, Guedat P, Mouly V, Butler-Browne G, Voisset C, Dickson G, Trollet C. Pharmacological modulation of the ER stress response ameliorates oculopharyngeal muscular dystrophy. Hum Mol Genet. 2019b;28:1694–708. [PubMed: 30649389]
• Manjaly JG, Vaughan-Shaw PG, Dale OT, Tyler S, Corlett JC, Frost RA. Cricopharyngeal dilatation for the long-term treatment of dysphagia in oculopharyngeal muscular dystrophy. Dysphagia. 2012;27:216–20. [PubMed: 21805106]
• Mathieu J, Lapointe G, Brassard A, Tremblay C, Brais B, Rouleau GA, Bouchard JP. A pilot study on upper oesophageal sphincter dilatation for the treatment of dysphagia in patients with oculopharyngeal muscular dystrophy. Neuromuscul Disord. 1997;7:S100–4. [PubMed: 9392026]
• McHorney CA, Robbins J, Lomax K, Rosenbek JC, Chignell K, Kramer AE, Bricker DE. The SWAL-QOL and SWAL-CARE outcomes tool for oropharyngeal dysphagia in adults: III. Documentation of reliability and validity. Dysphagia. 2002;17:97–114. [PubMed: 11956835]
• Montgomery WW, Lynch JP. Oculopharyngeal muscular dystrophy treated by inferior constrictor myotomy. Trans Am Acad Ophthalmol Otolaryngol. 1971;75:986–93. [PubMed: 5097831]
• Patel DA, Sharda R, Hovis KL, Nichols EE, Sathe N, Penson DF, Feurer ID, McPheeters ML, Vaezi MF, Francis DO. Patient-reported outcome measures in dysphagia: a systematic review of instrument development and validation. Dis Esophagus. 2017;30:1–23. [PMC free article: PMC5675017] [PubMed: 28375450]
• Périé S, Eymard B, Laccourreye L, Chaussade S, Fardeau M, Lacau St Guily J. Dysphagia in oculopharyngeal muscular dystrophy: a series of 22 French cases. Neuromuscul Disord. 1997;7 Suppl 1:S96–9. [PubMed: 9392025]
• Périé S, Laccourreye L, Flahault A, Hazebroucq V, Chaussade S, St Guily JL. Role of videoendoscopy in assessment of pharyngeal function in oropharyngeal dysphagia: comparison with videofluoroscopy and manometry. Laryngoscope. 1998;108:1712–6. [PubMed: 9818831]
• Périé S, Trollet C, Mouly V, Vanneaux V, Mamchaoui K, Bouazza B, Marolleau JP, Laforêt P, Chapon F, Eymard B, Butler-Browne G, Larghero J, St Guily JL. Autologous myoblast transplantation for oculopharyngeal muscular dystrophy: a phase I/IIa clinical study. Mol Ther. 2014;22:219–25. [PMC free article: PMC3978797] [PubMed: 23831596]
• Probst A, Tackmann W, Stoeckli HR, Jerusalem F, Ulrich J. Evidence for a chronic axonal atrophy in oculopharyngeal "muscular dystrophy". Acta Neuropathol. 1982;57:209–16. [PubMed: 7124348]
• Rahbari R, Wuster A, Lindsay SJ, Hardwick RJ, Alexandrov LB, Turki SA, Dominiczak A, Morris A, Porteous D, Smith B, Stratton MR, Hurles ME, et al. Timing, rates and spectra of human germline mutation. Nat Genet. 2016;48:126–33. [PMC free article: PMC4731925] [PubMed: 26656846]
• Raz V, Butler-Browne G, van Engelen B, Brais B. 191st ENMC international workshop: recent advances in oculopharyngeal muscular dystrophy research: from bench to bedside 8-10 June 2012, Naarden, The Netherlands. Neuromuscul Disord. 2013;23:516–23. [PubMed: 23578714]
• Restivo DA, Marchese RR, Staffieri A, de Grandis D. Successful botulinum toxin treatment of dysphagia in oculopharyngeal muscular dystrophy. Gastroenterology. 2000;119:1416. [PubMed: 11185464]
• Richard P, Trollet C, Gidaro T, Demay L, Brochier G, Malfatti E, Tom FM, Fardeau M, Lafor P, Romero N, Martin-N ML, Sol G, Ferrer-Monasterio X, Saint-Guily JL, Eymard B. PABPN1 (GCN)11 as a dominant allele in oculopharyngeal muscular dystrophy -consequences in clinical diagnosis and genetic counselling. J Neuromuscul Dis. 2015;2:175–80. [PMC free article: PMC5271460] [PubMed: 27858728]
• Richard P, Trollet C, Stojkovic T, de Becdelievre A, Perie S, Pouget J, Eymard B, et al. Correlation between PABPN1 genotype and disease severity in oculopharyngeal muscular dystrophy. Neurology. 2017;88:359–65. [PMC free article: PMC5272966] [PubMed: 28011929]
• Richards S, Aziz N, Bale S, Bick D, Das S, Gastier-Foster J, Grody WW, Hegde M, Lyon E, Spector E, Voelkerding K, Rehm HL., ACMG Laboratory Quality Assurance Committee. Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med. 2015;17:405–24. [PMC free article: PMC4544753] [PubMed: 25741868]
• Robinson DO, Hammans SR, Read SP, Sillibourne J. Oculopharyngeal muscular dystrophy (OPMD): analysis of the PABPN1 gene expansion sequence in 86 patients reveals 13 different expansion types and further evidence for unequal recombination as the mutational mechanism. Hum Genet. 2005;116:267–71. [PubMed: 15645184]
• Rodrigue D, Molgat YM. Surgical correction of blepharoptosis in oculopharyngeal muscular dystrophy. Neuromuscul Disord. 1997;7:S82–4. [PubMed: 9392022]
• Rüegg S, Lehky Hagen M, Hohl U, Kappos L, Fuhr P, Plasilov M, Müller H, Heinimann K. Oculopharyngeal muscular dystrophy - an under-diagnosed disorder? Swiss Med Wkly. 2005;135:574–86. [PubMed: 16333769]
• Salassa JR. A functional outcome swallowing scale for staging oropharyngeal dysphagia. Dig Dis. 1999;17:230–4. [PubMed: 10754363]
• Satoyoshi E, Kinoshita M. Oculopharyngodistal myopathy. Arch Neurol. 1977;34:89–92. [PubMed: 836191]
• Schneider I, Thumfart WF, Pototschnig C, Eckel HE. Treatment of dysfunction of the cricopharyngeal muscle with botulinum A toxin: introduction of a new, noninvasive method. Ann Otol Rhinol Laryngol. 1994;103:31–5. [PubMed: 8291857]
• Schober R, Kress W, Grahmann F, Kellermann S, Baum P, Günzel S, Wagner A. Unusual triplet expansion associated with neurogenic changes in a family with oculopharyngeal muscular dystrophy. Neuropathology. 2001;21:45–52. [PubMed: 11304042]
• Schotland DL, Rowland LP. Muscular dystrophy. Features of ocular myopathy, distal myopathy, and myotonic dystrophy. Arch Neurol. 1964;10:433–45. [PubMed: 14120634]
• Scrimgeour EM, Mastaglia FL. Oculopharyngeal and distal myopathy: a case study from Papua New Guinea. Am J Med Genet. 1984;17:763–71. [PubMed: 6720743]
• Shahrizaila N, Kinnear WJ, Wills AJ. Respiratory involvement in inherited primary muscle conditions. J Neurol Neurosurg Psychiatry. 2006;77:1108–15. [PMC free article: PMC2077539] [PubMed: 16980655]
• Shan J, Chen B, Lin P, Li D, Luo Y, Ji K, Zheng J, Yuan Y, Yan C. Oculopharyngeal muscular dystrophy: phenotypic and genotypic studies in a Chinese population. Neuromolecular Med. 2014;16:782–6. [PubMed: 25283883]
• Silbergleit AK, Schultz L, Jacobson BH, Beardsley T, Johnson AF. The dysphagia handicap index: development and validation. Dysphagia. 2012;27:46–52. [PubMed: 21424584]
• St Guily JL, Moine A, Périé S, Bokowy C, Angelard B, Chaussade S. Role of pharyngeal propulsion as an indicator for upper esophageal sphincter myotomy. Laryngoscope. 1995;105:723–7. [PubMed: 7603277]
• St Guily JL, Périé S, Willig TN, Chaussade S, Eymard B, Angelard B. Swallowing disorders in muscular diseases: functional assessment and indications of cricopharyngeal myotomy. Ear Nose Throat J. 1994;73:34–40. [PubMed: 8162870]
• Tabor LC, Plowman EK, Romero-Clark C, Youssof S. Oropharyngeal dysphagia profiles in individuals with oculopharyngeal muscular dystrophy. Neurogastroenterol Motil. 2018;30:e13251. [PMC free article: PMC5878694] [PubMed: 29144056]
• Tomé F, Fardeau M. Oculopharyngeal muscular dystrophy. In: Myology. New York, NY: McGraw-Hill; 1994:1233-45.
• Tomé FM, Chateau D, Helbling-Leclerc A, Fardeau M. Morphological changes in muscle fibers in oculopharyngeal muscular dystrophy. Neuromuscul Disord. 1997;7:S63–9. [PubMed: 9392019]
• Tomé FM, Fardeau M. Nuclear inclusions in oculopharyngeal dystrophy. Acta Neuropathol (Berl). 1980;49:85–7. [PubMed: 6243839]
• Tondo M, Gámez J, Gutiérrez-Rivas E, Medel-Jiménez R, Martorell L. Genotype and phenotype study of 34 Spanish patients diagnosed with oculopharyngeal muscular dystrophy. J Neurol. 2012;259:1546–52. [PubMed: 22231868]
• van der Sluijs BM, Knoop H, Bleijenberg G, van Engelen BG, Voermans NC. The Dutch patients' perspective on oculopharyngeal muscular dystrophy: A questionnaire study on fatigue, pain and impairments. Neuromuscul Disord. 2016;26:221–6. [PubMed: 26948710]
• Verheesen P, de Kluijver A, van Koningsbruggen S, de Brij M, de Haard HJ, van Ommen GJ, van der Maarel SM, Verrips CT. Prevention of oculopharyngeal muscular dystrophy-associated aggregation of nuclear polyA-binding protein with a single-domain intracellular antibody. Hum Mol Genet. 2006;15:105–11. [PubMed: 16319127]
• Vest KE, Phillips BL, Banerjee A, Apponi LH, Dammer EB, Xu W, Zheng D, Yu J, Tian B, Pavlath GK, Corbett AH. Novel mouse models of oculopharyngeal muscular dystrophy (OPMD) reveal early onset mitochondrial defects and suggest loss of PABPN1 may contribute to pathology. Hum Mol Genet. 2017;26:3235–52. [PMC free article: PMC5886286] [PubMed: 28575395]
• Victor M, Hayes R, Adams RD. Oculopharyngeal muscular dystrophy. A familial disease of late life characterized by dysphagia and progressive ptosis of the evelids. N Engl J Med. 1962;267:1267–72. [PubMed: 13997067]
• Vita G, Dattola R, Santoro M, Messina C. Familial oculopharyngeal muscular dystrophy with distal spread. J Neurol. 1983;230:57–64. [PubMed: 6194273]
• Waito AA, Steele CM, Peladeau-Pigeon M, Genge A, Argov Z. A Preliminary videofluoroscopic investigation of swallowing physiology and function in individuals with oculopharyngeal muscular dystrophy (OPMD). Dysphagia. 2018;33:789–802. [PubMed: 29725764]
• Wang Q, Mosser DD, Bag J. Induction of HSP70 expression and recruitment of HSC70 and HSP70 in the nucleus reduce aggregation of a polyalanine expansion mutant of PABPN1 in HeLa cells. Hum Mol Genet. 2005;14:3673–84. [PubMed: 16239242]
• Witting N, Mensah A, Kober L, Bundgaard H, Petri H, Duno M, et al. Ocular, bulbar, limb, and cardiopulmonary involvement in oculopharyngeal muscular dystrophy. Acta Neurol Scand. 2014;130:125–30. [PubMed: 24611576]