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THOC6-related developmental delay-microcephaly-facial dysmorphism syndrome(BBIS)

MedGen UID:
462289
Concept ID:
C3150939
Disease or Syndrome
Synonyms: Beaulieu-Boycott-Innes syndrome; Microcephaly, mental retardation, and distinctive facies, with cardiac and genitourinary malformations
SNOMED CT: THO complex 6-related developmental delay, microcephaly, facial dysmorphism syndrome (773554009); THOC6-related developmental delay-microcephaly-facial dysmorphism syndrome (773554009); Beaulieu Boycott Innes syndrome (773554009); BBIS - Beaulieu Boycott Innes syndrome (773554009)
Modes of inheritance:
Autosomal recessive inheritance
MedGen UID:
141025
Concept ID:
C0441748
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele).
 
Gene (location): THOC6 (16p13.3)
 
Monarch Initiative: MONDO:0013362
OMIM®: 613680
Orphanet: ORPHA363444

Disease characteristics

Excerpted from the GeneReview: THOC6 Intellectual Disability Syndrome
THOC6 intellectual disability syndrome is associated with moderate-to-severe developmental delay or intellectual disability; nonspecific dysmorphic facial features (tall forehead, deep-set eyes, short and upslanted palpebral fissures, epicanthal folds, and long nose with low-hanging columella); microcephaly (typically 2-3 SD below the mean); teeth anomalies (dental caries, malocclusion, and supernumerary teeth); cardiac anomalies (most typically atrial and/or ventricular septal defects); prenatal ventriculomegaly and hydrocephalus; cryptorchidism in males; and renal malformations (most commonly unilateral renal agenesis). More rarely, affected individuals may have hypergonadotropic hypogonadism (in females), seizures, poor growth, feeding difficulties, hearing loss, refractive errors and/or other eye abnormalities, vertebral anomalies, micro/retrognathia, and imperforate / anteriorly placed anus. [from GeneReviews]
Authors:
Gabrielle Lemire  |  A Micheil Innes  |  Kym M Boycott   view full author information

Additional description

From OMIM
Beaulieu-Boycott-Innes syndrome (BBIS) is an autosomal recessive neurodevelopmental disorder characterized by delayed development, moderate to severe intellectual disability, and dysmorphic facial features. Other developmental anomalies, such as cardiac and renal defects, cryptorchidism in males, submucous cleft palate, and corpus callosum dysgenesis, may also be present (summary by Beaulieu et al., 2013 and Amos et al., 2017).  http://www.omim.org/entry/613680

Clinical features

From HPO
Endometriosis
MedGen UID:
8620
Concept ID:
C0014175
Disease or Syndrome
The growth of endometrial tissue outside the uterus.
Premature ovarian insufficiency
MedGen UID:
9963
Concept ID:
C0025322
Disease or Syndrome
Amenorrhea due to loss of ovarian function before the age of 40. Primary ovarian inssuficiency (POI) is a state of female hypergonadotropic hypogonadism. It can manifest as primary amenorrhea with onset before menarche or secondary amenorrhea.
Horseshoe kidney
MedGen UID:
65140
Concept ID:
C0221353
Congenital Abnormality
A connection of the right and left kidney by an isthmus of functioning renal parenchyma or fibrous tissue that crosses the midline.
Recurrent urinary tract infections
MedGen UID:
120466
Concept ID:
C0262655
Disease or Syndrome
Repeated infections of the urinary tract.
Unilateral renal agenesis
MedGen UID:
75607
Concept ID:
C0266294
Congenital Abnormality
A unilateral form of agenesis of the kidney.
Patent ductus arteriosus
MedGen UID:
4415
Concept ID:
C0013274
Congenital Abnormality
In utero, the ductus arteriosus (DA) serves to divert ventricular output away from the lungs and toward the placenta by connecting the main pulmonary artery to the descending aorta. A patent ductus arteriosus (PDA) in the first 3 days of life is a physiologic shunt in healthy term and preterm newborn infants, and normally is substantially closed within about 24 hours after bith and completely closed after about three weeks. Failure of physiologcal closure is referred to a persistent or patent ductus arteriosus (PDA). Depending on the degree of left-to-right shunting, PDA can have clinical consequences.
Ventricular septal defect
MedGen UID:
42366
Concept ID:
C0018818
Congenital Abnormality
A hole between the two bottom chambers (ventricles) of the heart. The defect is centered around the most superior aspect of the ventricular septum.
Global developmental delay
MedGen UID:
107838
Concept ID:
C0557874
Finding
A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.
Intellectual disability
MedGen UID:
811461
Concept ID:
C3714756
Mental or Behavioral Dysfunction
Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.
Micrognathia
MedGen UID:
44428
Concept ID:
C0025990
Congenital Abnormality
Developmental hypoplasia of the mandible.
Microcephaly
MedGen UID:
1644158
Concept ID:
C4551563
Finding
Head circumference below 2 standard deviations below the mean for age and gender.
Carious teeth
MedGen UID:
8288
Concept ID:
C0011334
Disease or Syndrome
Caries is a multifactorial bacterial infection affecting the structure of the tooth. This term has been used to describe the presence of more than expected dental caries.
Dental malocclusion
MedGen UID:
9869
Concept ID:
C0024636
Anatomical Abnormality
Dental malocclusion refers to an abnormality of the occlusion, or alignment, of the teeth and the way the upper and lower teeth fit together, resulting in overcrowding of teeth or in abnormal bite patterns.
Velopharyngeal insufficiency
MedGen UID:
52992
Concept ID:
C0042454
Finding
Inability of velopharyngeal sphincter to sufficiently separate the nasal cavity from the oral cavity during speech.
High forehead
MedGen UID:
65991
Concept ID:
C0239676
Finding
An abnormally increased height of the forehead.
Upslanted palpebral fissure
MedGen UID:
98390
Concept ID:
C0423109
Finding
The palpebral fissure inclination is more than two standard deviations above the mean for age (objective); or, the inclination of the palpebral fissure is greater than typical for age.
Short palpebral fissure
MedGen UID:
98067
Concept ID:
C0423112
Finding
Distance between the medial and lateral canthi is more than 2 SD below the mean for age (objective); or, apparently reduced length of the palpebral fissures.
Long nose
MedGen UID:
326583
Concept ID:
C1839798
Finding
Distance from nasion to subnasale more than two standard deviations above the mean, or alternatively, an apparently increased length from the nasal root to the nasal base.
Low hanging columella
MedGen UID:
344656
Concept ID:
C1856119
Finding
Columella extending inferior to the level of the nasal base, when viewed from the side.
High anterior hairline
MedGen UID:
477667
Concept ID:
C3276036
Finding
Distance between the hairline (trichion) and the glabella (the most prominent point on the frontal bone above the root of the nose), in the midline, more than two SD above the mean. Alternatively, an apparently increased distance between the hairline and the glabella.
Myopia
MedGen UID:
44558
Concept ID:
C0027092
Disease or Syndrome
Nearsightedness, also known as myopia, is an eye condition that causes blurry distance vision. People who are nearsighted have more trouble seeing things that are far away (such as when driving) than things that are close up (such as when reading or using a computer). If it is not treated with corrective lenses or surgery, nearsightedness can lead to squinting, eyestrain, headaches, and significant visual impairment.\n\nNearsightedness usually begins in childhood or adolescence. It tends to worsen with age until adulthood, when it may stop getting worse (stabilize). In some people, nearsightedness improves in later adulthood.\n\nFor normal vision, light passes through the clear cornea at the front of the eye and is focused by the lens onto the surface of the retina, which is the lining of the back of the eye that contains light-sensing cells. People who are nearsighted typically have eyeballs that are too long from front to back. As a result, light entering the eye is focused too far forward, in front of the retina instead of on its surface. It is this change that causes distant objects to appear blurry. The longer the eyeball is, the farther forward light rays will be focused and the more severely nearsighted a person will be.\n\nNearsightedness is measured by how powerful a lens must be to correct it. The standard unit of lens power is called a diopter. Negative (minus) powered lenses are used to correct nearsightedness. The more severe a person's nearsightedness, the larger the number of diopters required for correction. In an individual with nearsightedness, one eye may be more nearsighted than the other.\n\nEye doctors often refer to nearsightedness less than -5 or -6 diopters as "common myopia." Nearsightedness of -6 diopters or more is commonly called "high myopia." This distinction is important because high myopia increases a person's risk of developing other eye problems that can lead to permanent vision loss or blindness. These problems include tearing and detachment of the retina, clouding of the lens (cataract), and an eye disease called glaucoma that is usually related to increased pressure within the eye. The risk of these other eye problems increases with the severity of the nearsightedness. The term "pathological myopia" is used to describe cases in which high myopia leads to tissue damage within the eye.
Deeply set eye
MedGen UID:
473112
Concept ID:
C0423224
Finding
An eye that is more deeply recessed into the plane of the face than is typical.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVTHOC6-related developmental delay-microcephaly-facial dysmorphism syndrome
Follow this link to review classifications for THOC6-related developmental delay-microcephaly-facial dysmorphism syndrome in Orphanet.

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