MedGen

GJB2-related autosomal recessive nonsyndromic hearing loss (GJB2-AR NSHL) is the most common genetic cause of congenital (present at birth) severe-to-profound non-progressive sensorineural hearing loss in many world populations. In countries where available, newborn hearing screening (NBHS) typically identifies severe-to-profound hearing loss. GJB2-AR NSHL can also be mild to moderate and is usually not progressive; however, it can progress. Congenital mild-to-moderate GJB2-AR NSHL is not detected by NBHS. GJB2-AR NSHL has no related systemic findings. [from GeneReviews]

SLC26A4-related sensorineural hearing loss (SLC26A4-SNHL), characterized by inner ear malformations also associated with vestibular dysfunction, comprises two phenotypes: (1) nonsyndromic SLC26A4-SNHL (also referred to as DFNB4 or nonsyndromic enlargement of the vestibular aqueduct [NSEVA]) and (2) Pendred syndrome (PDS) that includes thyroid involvement (typically identified more frequently in countries without universal salt iodization programs). The time of onset and type of presentation of the SNHL vary (such that some newborns pass their newborn hearing screening); however, by age three years most children have bilateral and severe-to-profound hearing loss. Manifestations of vestibular dysfunction (such as head-tilting, vomiting, and/or delayed ambulation or clumsiness in a child who previously walked well) can precede or accompany the fluctuations in hearing typical of this disorder. Thyroid enlargement (goiter) occurs gradually and is typically evident in the second decade, especially if iodine is not routinely included in the diet. [from GeneReviews]

Episodic ataxia is a genetically heterogeneous neurologic condition characterized by spells of incoordination and imbalance, often associated with progressive ataxia. Episodic ataxia type 2 is the most common form of EA (Jen et al., 2007). For a discussion of genetic heterogeneity of episodic ataxia, see EA1 (160120). [from OMIM]

Usher syndrome type I (USH1) is characterized by congenital, bilateral, profound sensorineural hearing loss, vestibular areflexia, and adolescent-onset retinitis pigmentosa (RP). Unless fitted with a cochlear implant, individuals do not typically develop speech. RP, a progressive, bilateral, symmetric degeneration of rod and cone functions of the retina, develops in adolescence, resulting in progressively constricted visual fields and impaired visual acuity. [from GeneReviews]

Usher syndrome type I (USH1) is characterized by congenital, bilateral, profound sensorineural hearing loss, vestibular areflexia, and adolescent-onset retinitis pigmentosa (RP). Unless fitted with a cochlear implant, individuals do not typically develop speech. RP, a progressive, bilateral, symmetric degeneration of rod and cone functions of the retina, develops in adolescence, resulting in progressively constricted visual fields and impaired visual acuity. [from GeneReviews]

POLG-related disorders comprise a continuum of overlapping phenotypes that were clinically defined before the molecular basis was known. POLG-related disorders can therefore be considered an overlapping spectrum of disease presenting from early childhood to late adulthood. The age of onset broadly correlates with the clinical phenotype. In individuals with early-onset disease (prior to age 12 years), liver involvement, feeding difficulties, seizures, hypotonia, and muscle weakness are the most common clinical features. This group has the worst prognosis. In the juvenile/adult-onset form (age 12-40 years), disease is typically characterized by peripheral neuropathy, ataxia, seizures, stroke-like episodes, and, in individuals with longer survival, progressive external ophthalmoplegia (PEO). This group generally has a better prognosis than the early-onset group. Late-onset disease (after age 40 years) is characterized by ptosis and PEO, with additional features such as peripheral neuropathy, ataxia, and muscle weakness. This group overall has the best prognosis. [from GeneReviews]

A genetic condition inherited in an autosomal recessive caused by mutation(s) in the CDH23 gene, encoding cadherin-23, characterized by progressive sensorineural hearing loss. Mutation(s) in the CDH23 gene may also cause Usher syndrome 1D. [from NCI]

Autosomal dominant deafness-11 is a nonsyndromic form of progressive neurosensory hearing loss with postlingual onset. Some affected individuals have mild vestibular symptoms (summary by Sun et al., 2011). [from OMIM]

Usher syndrome type I (USH1) is characterized by congenital, bilateral, profound sensorineural hearing loss, vestibular areflexia, and adolescent-onset retinitis pigmentosa (RP). Unless fitted with a cochlear implant, individuals do not typically develop speech. RP, a progressive, bilateral, symmetric degeneration of rod and cone functions of the retina, develops in adolescence, resulting in progressively constricted visual fields and impaired visual acuity. [from GeneReviews]

Any autosomal recessive nonsyndromic deafness in which the cause of the disease is a mutation in the MYO7A gene. [from MONDO]

Any autosomal recessive nonsyndromic deafness in which the cause of the disease is a mutation in the GJB6 gene. [from MONDO]

Any autosomal recessive nonsyndromic deafness in which the cause of the disease is a mutation in the LOXHD1 gene. [from MONDO]

Usher syndrome type II (USH2) is characterized by the following: Congenital, bilateral sensorineural hearing loss that is mild to moderate in the low frequencies and severe to profound in the higher frequencies. Intact or variable vestibular responses. Retinitis pigmentosa (RP); progressive, bilateral, symmetric retinal degeneration that begins with night blindness and constricted visual fields (tunnel vision) and eventually includes decreased central visual acuity; the rate and degree of vision loss vary within and among families. [from GeneReviews]

Any autosomal recessive nonsyndromic deafness in which the cause of the disease is a mutation in the TMC1 gene. [from MONDO]

Any autosomal dominant nonsyndromic deafness in which the cause of the disease is a mutation in the SLC17A8 gene. [from MONDO]

Any autosomal recessive nonsyndromic deafness in which the cause of the disease is a mutation in the LRTOMT gene. [from MONDO]

Autosomal recessive deafness-67 (DFNB67) is characterized by congenital bilateral severe to profound sensorineural deafness, with or without vestibular dysfunction (Shabbir et al., 2006; Kalay et al., 2006; Lerat et al., 2019). [from OMIM]

DFNB48 is an autosomal recessive form of deafness. Affected individuals have prelingual onset of severe to profound sensorineural hearing loss affecting all frequencies (summary by Riazuddin et al., 2012). [from OMIM]

Any autosomal recessive nonsyndromic deafness in which the cause of the disease is a mutation in the MYO6 gene. [from MONDO]

Usher syndrome type I (USH1) is characterized by congenital, bilateral, profound sensorineural hearing loss, vestibular areflexia, and adolescent-onset retinitis pigmentosa (RP). Unless fitted with a cochlear implant, individuals do not typically develop speech. RP, a progressive, bilateral, symmetric degeneration of rod and cone functions of the retina, develops in adolescence, resulting in progressively constricted visual fields and impaired visual acuity. [from GeneReviews]