Hearing loss features in GJB2 biallelic mutations and GJB2/GJB6 digenic inheritance in a large Italian cohort.
The aim of this study was to describe the clinical features of hearing loss due to mutations on connexin 26/30 coding genes (GJB2/GJB6). Mutations in the GJB2 gene are found to account for approximately 50% of cases of autosomal recessive non-syndromic deafness. Several European studies have estimated that the GJB2 healthy carrier condition involves about 2-4% of the population, with the 35delG mutations being the most common. A 342-kb deletion truncating the GJB6 gene (encoding connexin-30) has been associated with autosomal recessive non-syndromic deafness, mostly as digenic inheritance of the Cx30 deletion/Cx26 mutation. The following retrospective study describes audiological features and genotypes of a large cohort of 376 Italian hearing-impaired patients who underwent genetic screening for the GJB2/GJB6 genes and received follow-up care at our centre between January 2002 and October 2006. Sixteen different genotypes causing deafness in more than 27% of patients with either biallelic mutations or digenic inheritance GJB2/GJB6 were identified. The most frequent mutations were 35delG, M34T, L90P, and R184P.
Cama
Elona
E
Servizio di Audiologia e Foniatria, Dipartimento Specialita Medico-Chirurgiche, University of Padua, Padova, Italy. elona.cama@unipd.it
Melchionda
Salvatore
S
Palladino
Teresa
T
Carella
Massimo
M
Santarelli
Rosamaria
R
Genovese
Elisabetta
E
Benettazzo
Filippo
F
Zelante
Leopoldo
L
Arslan
Edoardo
E
D000158:Acoustic Impedance Tests; D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D001301:Audiometry, Pure-Tone; D001307:Auditory Perception; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D000072259:Connexin 26; D000075302:Connexin 30; D017630:Connexins / Q000235:genetics*; D018450:Disease Progression; D005260:Female; D020022:Genetic Predisposition to Disease; D006319:Hearing Loss, Sensorineural / Q000235:genetics* / Q000503:physiopathology; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007223:Infant; D040582:Inheritance Patterns; D007558:Italy; D008297:Male; D008875:Middle Aged; D009154:Mutation; D038781:Otoscopy; D010641:Phenotype; D012022:Reflex, Acoustic; D012189:Retrospective Studies; D055815:Young Adult
D000075302:Connexin 30; D017630:Connexins; C000607042:GJB2 protein, human; C491020:GJB6 protein, human; D000072259:Connexin 26