Clinical Studies of Families With Hearing Loss Attributable to Mutations in the Connexin 26 Gene (GJB2/DFNB1)

Clinical Studies of Families With Hearing Loss Attributable to Mutations in the Connexin 26 Gene (GJB2/DFNB1)

This retrospective study describes the phenotype associated with the single most common cause of genetic hearing loss. The frequency of childhood deafness is estimated at 1/500. Half of this hearing loss is genetic and approximately 80% of genetic hearing loss is nonsyndromic and inherited in an aut...

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Bibliographic Details
Published in:Pediatrics (Evanston) Vol. 103; no. 3; pp. 546 - 550
Main Authors: Cohn, Edward S, Kelley, Philip M, Fowler, Thomas W, Gorga, Michael P, Lefkowitz, David M, Kuehn, Harold J, Schaefer, G. Bradley, Gobar, Lisa S, Hahn, Francis J, Harris, Djuana J, Kimberling, William J
Format: Journal Article
Language:English
Published: Elk Grove Village, IL Am Acad Pediatrics 01-03-1999
American Academy of Pediatrics
Subjects:
Biological and medical sciences
Child
Connexin 26
Connexins - genetics
Deafness
Disease Progression
Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology
Female
Genes
Genetic aspects
Genetics
Hearing disorders
Hearing Loss, Sensorineural - genetics
Heterozygote
Homozygote
Humans
Male
Medical sciences
Mutation
Non tumoral diseases
Otorhinolaryngology. Stomatology
Pediatrics
Retrospective Studies
United States
North America
America
Human
Connexin
Phenotype
Gene
Auditory disorder
ENT disease
Evolution
Mutation
Genetic determinism
Comparative study
Hearing loss
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Summary:This retrospective study describes the phenotype associated with the single most common cause of genetic hearing loss. The frequency of childhood deafness is estimated at 1/500. Half of this hearing loss is genetic and approximately 80% of genetic hearing loss is nonsyndromic and inherited in an autosomal recessive manner. Approximately 50% of childhood nonsyndromic recessive hearing loss is caused by mutations in the connexin 26 (Cx26) gene (GJB2/DFNB1), making it the most common form of autosomal recessive nonsyndromic hearing loss with a carrier rate estimated to be as high as 2.8%. One mutation, 35delG, accounts for approximately 75% to 80% of mutations at this gene. Hearing loss was examined in 46 individuals from 24 families who were either homozygous or compound heterozygous for Cx26 mutations. A subset of these individuals were examined for vestibular function, otoacoustic emissions, auditory brainstem response, temporal bone computed tomography, electrocardiography, urinalyses, dysmorphology, and thyroid function. Although all persons had hearing impairment, no consistent audiologic phenotype was observed. Hearing loss varied from mild-moderate to profound, even within the group of families homozygous for the common mutation 35delG, suggesting that other factors modify the phenotypic effects of mutations in Cx26. Furthermore, the hearing loss was observed to be progressive in a number of cases. No associations with inner ear abnormality, thyroid dysfunction, heart conduction defect, urinalyses, dysmorphic features, or retinal abnormality were noted. Newborns with confirmed hearing loss should have Cx26 testing. Cx26 testing will help define a group in which approximately 60% will have profound or severe-profound hearing loss and require aggressive language intervention (many of these patients will be candidates for cochlear implants).
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ISSN:0031-4005
1098-4275
DOI:10.1542/peds.103.3.546