MedGen

Syndromic microphthalmia-16 (MCOPS16) is characterized by bilateral severe microphthalmia or anophthalmia with variable presence of midline defects, including cleft lip and palate, absence of frontal and/or sphenoidal sinuses, and absent pituitary gland. Some patients exhibit developmental delay and intellectual disability or autism (Voronina et al., 2004; Abouzeid et al., 2012; Chassaing et al., 2014; Brachet et al., 2019). For discussion of the genetic heterogeneity of syndromic microphthalmia, see MCOPS1 (309800). [from OMIM]

Immune dysregulation and systemic hyperinflammation syndrome (IMDYSHI) is an autosomal recessive immunologic disorder characterized by systemic hyperinflammation in the absence of an infectious agent or autoimmune trigger. Features include lymphadenopathy, hepatosplenomegaly, recurrent fever, and laboratory evidence of immune dysregulation with abnormal immune cell populations and increased serum levels of inflammatory cytokines. The phenotype is reminiscent of relapsing hemophagocytic lymphohistiocytosis (HLH; see FHL1, 267700) (summary by Tavernier et al., 2019). [from OMIM]

Hereditary primary lymphedema is caused by anatomic or functional defects in the lymphatic system, resulting in chronic swelling of body parts. There may be accompanying nail and skin changes, such as nail dysplasia or papillomatosis. Onset is usually at birth or in early childhood but can occur later, and the severity is variable (summary by Gordon et al., 2013 and Balboa-Beltran et al., 2014). For a discussion of genetic heterogeneity of lymphatic malformation, see 153100. [from OMIM]

Any hereditary lymphedema in which the cause of the disease is a mutation in the VEGFC gene. [from MONDO]

Hereditary primary lymphedema is caused by anatomic or functional defects in the lymphatic system, resulting in chronic swelling of body parts. There may be accompanying nail and skin changes, such as nail dysplasia or papillomatosis. Onset is usually at birth or in early childhood but can occur later, and the severity is variable (summary by Gordon et al., 2013 and Balboa-Beltran et al., 2014). For a discussion of genetic heterogeneity of lymphatic malformation, see 153100. [from OMIM]

Impaired proliferation and expansion of a T cell population following activation by an antigenic stimulus. [from HPO]

Immunodeficiency-51 (IMD51) is an autosomal recessive primary immune deficiency that is usually characterized by onset of chronic mucocutaneous candidiasis in the first years of life. Most patients also show recurrent Staphylococcal skin infections, and may show increased susceptibility to chronic bacterial respiratory infections. Patient cells show a lack of cellular responses to stimulation with certain IL17 isoforms, including IL17A (603149), IL17F (606496), IL17A/F, and IL17E (IL25; 605658) (summary by Levy et al., 2016). [from OMIM]

Neurodevelopmental disorder with or without hypotonia, seizures, and cerebellar atrophy (NEDHSCA) is an autosomal recessive disorder characterized by severely delayed psychomotor development, hypotonia apparent since infancy, and early-onset seizures in most patients. Some patients may have additional features, such as cerebellar atrophy, ataxia, and nonspecific dysmorphic features. NEDHSCA is one of a group of similar neurologic disorders resulting from biochemical defects in the glycosylphosphatidylinositol (GPI) biosynthetic pathway. Some patients with NEDHSCA may have the Emm-null blood group phenotype (see 619812) (summary by Makrythanasis et al., 2016; Duval et al., 2021). For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293). [from OMIM]

Neurodevelopmental disorder with microcephaly and gray sclerae (NEDMIGS) is a severe autosomal recessive disorder characterized by impaired global development with hypotonia often precluding independent ambulation, profoundly impaired intellectual development with poor or absent language, mild microcephaly, and abnormal visual fixation. Patients also have gray sclerae and may have coarse facial features. Most affected individuals have seizures; some may have brain imaging abnormalities (summary by Shaheen et al., 2016 and Froukh et al., 2020). [from OMIM]

PERCHING syndrome is an autosomal recessive multisystem disorder characterized by global developmental delay, dysmorphic facial features, feeding and respiratory difficulties with poor overall growth, axial hypotonia, and joint contractures. The features are variable, even within families, and may also include retinitis pigmentosa, cardiac or genitourinary anomalies, and abnormal sweating. Each letter of the PERCHING acronym represents 2 important phenotypic elements: Postural and Palatal abnormalities; Exophthalmos and Enteral-tube dependency/feeding issues; Respiratory distress and Retinitis pigmentosa; Contractures and Camptodactyly; Hypertelorism and Hirsutism; Intrauterine growth retardation (IUGR)/growth failure and Intellectual disability/developmental delay; Nevus flammeus and Neurologic malformations; and facial Gestalt/grimacing and Genitourinary abnormalities (Jeffries et al., 2019). Death in infancy or early childhood often occurs, although survival to the third decade has been reported. Some of the features, such as contractures, dysmorphic craniofacial features, and severe feeding difficulties, are reminiscent of Bohring-Opitz syndrome (605039) (summary by Kanthi et al., 2019 and Buers et al., 2020). [from OMIM]

MRT74 is characterized by intellectual impairment, macrocephaly, and dysmorphic features. Epilepsy with eyelid myoclonus has also been reported (Almuriekhi et al., 2015; Mastrangelo et al., 2020). [from OMIM]

Slow-channel congenital myasthenic syndrome (SCCMS) is a disorder of the postsynaptic neuromuscular junction (NMJ) characterized by early-onset progressive muscle weakness. The disorder results from kinetic abnormalities of the acetylcholine receptor channel, specifically from prolonged opening and activity of the channel, which causes prolonged synaptic currents resulting in a depolarization block. This is associated with calcium overload, which may contribute to subsequent degeneration of the endplate and postsynaptic membrane. Treatment with quinine, quinidine, or fluoxetine may be helpful; acetylcholinesterase inhibitors and amifampridine should be avoided (summary by Engel et al., 2015). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462). [from OMIM]

Neurodevelopmental disorder with spastic paraplegia and microcephaly (NEDSPM) is an autosomal recessive neurologic syndrome characterized by delayed psychomotor development with delayed walking, moderately to severely impaired intellectual development, and poor or absent speech. More severely affected individuals show poor overall growth with progressive microcephaly, axial hypotonia, oromotor dysfunction with drooling, joint contractures, and spastic paraplegia resulting in walking difficulties. Some patients may develop seizures; nonspecific dysmorphic features have also been reported (summary by Hengel et al., 2018 and Ouyang et al., 2019). [from OMIM]

Developmental and epileptic encephalopathy-50 (DEE50) is an autosomal recessive progressive neurodegenerative neurometabolic disorder characterized by delayed psychomotor development, early-onset refractory seizures, severe developmental regression, and normocytic anemia. Onset is within the first months or years of life. Evidence suggests that affected children can have a favorable response to treatment with uridine (summary by Koch et al., 2017). For a discussion of genetic heterogeneity of DEE, see 308350. [from OMIM]

Arboleda-Tham syndrome (ARTHS) is an autosomal dominant disorder with the core features of impaired intellectual development, speech delay, microcephaly, cardiac anomalies, and gastrointestinal complications (summary by Kennedy et al., 2019). [from OMIM]

Congenital myasthenic syndrome associated with AChR deficiency is a disorder of the postsynaptic neuromuscular junction (NMJ) clinically characterized by early-onset muscle weakness with variable severity. Electrophysiologic studies show low amplitude of the miniature endplate potential (MEPP) and current (MEPC) resulting from deficiency of AChR at the endplate. Treatment with cholinesterase inhibitors or amifampridine may be helpful (summary by Engel et al., 2015). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462). [from OMIM]

Any hypertrophic cardiomyopathy in which the cause of the disease is a mutation in the TCAP gene. [from MONDO]

The phenotypic spectrum of SERAC1 deficiency comprises MEGD(H)EL syndrome (3-methylglutaconic aciduria with deafness-dystonia, [hepatopathy], encephalopathy, and Leigh-like syndrome), juvenile-onset complicated hereditary spastic paraplegia (in 1 consanguineous family), and adult-onset generalized dystonia (in 1 adult male). MEGD(H)EL syndrome is characterized in neonates by hypoglycemia and a sepsis-like clinical picture for which no infectious agent can be found. During the first year of life feeding problems, failure to thrive, and/or truncal hypotonia become evident; many infants experience (transient) liver involvement ranging from undulating transaminases to prolonged hyperbilirubinemia and near-fatal liver failure. By age two years progressive deafness, dystonia, and spasticity prevent further psychomotor development and/or result in loss of acquired skills. Affected children are completely dependent on care for all activities of daily living; speech is absent. [from GeneReviews]

Autosomal recessive congenital ichthyosis (ARCI) encompasses several forms of nonsyndromic ichthyosis. Although most neonates with ARCI are collodion babies, the clinical presentation and severity of ARCI may vary significantly, ranging from harlequin ichthyosis, the most severe and often fatal form, to lamellar ichthyosis (LI) and (nonbullous) congenital ichthyosiform erythroderma (CIE). These phenotypes are now recognized to fall on a continuum; however, the phenotypic descriptions are clinically useful for clarification of prognosis and management. Infants with harlequin ichthyosis are usually born prematurely and are encased in thick, hard, armor-like plates of cornified skin that severely restrict movement. Life-threatening complications in the immediate postnatal period include respiratory distress, feeding problems, and systemic infection. Collodion babies are born with a taut, shiny, translucent or opaque membrane that encases the entire body and lasts for days to weeks. LI and CIE are seemingly distinct phenotypes: classic, severe LI with dark brown, plate-like scale with no erythroderma and CIE with finer whiter scale and underlying generalized redness of the skin. Affected individuals with severe involvement can have ectropion, eclabium, scarring alopecia involving the scalp and eyebrows, and palmar and plantar keratoderma. Besides these major forms of nonsyndromic ichthyosis, a few rare subtypes have been recognized, such as bathing suit ichthyosis, self-improving collodion ichthyosis, or ichthyosis-prematurity syndrome. [from GeneReviews]

Autoimmune lymphoproliferative syndrome type III is an autosomal recessive disorder of immune dysregulation. The phenotype is variable, but most patients have significant lymphadenopathy associated with variable autoimmune manifestations. Some patients may have recurrent infections. Lymphocyte accumulation results from a combination of impaired apoptosis and excessive proliferation (summary by Oliveira, 2013). For a general description and a discussion of genetic heterogeneity of ALPS, see 601859. [from OMIM]