Compound heterozygosity for dominant and recessive GJB2 mutations in a Tunisian family and association with successful cochlear implant outcome

Abstract Objectives Mutations of GJB2 encoding connexin 26 are the most common cause of hearing loss. They are responsible for up to 50% of ARNSHL. The pathogenic mutations in this gene are generally inherited recessively. Dominant mutations in GJB2 also cause hearing loss, either in isolated non-sy...

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Published in:International journal of pediatric otorhinolaryngology 2013-09, Vol.77 (9), p.1481-1484
Main Authors: Riahi, Zied, Zainine, Rim, Mellouli, Yosra, Hannachi, Raja, Bouyacoub, Yosra, Laroussi, Nadia, Beltaief, Najeh, Kefi, Rym, Romdhane, Lilia, Bonnet, Crystel, Abdelhak, Sonia, Besbes, Ghazi
Format: Article
Language:English
Subjects:
Audiometry
Child, Preschool
Cochlear implant
Cochlear Implantation - methods
Cochlear Implants
Connexin 26
Connexins - genetics
Deafness - genetics
Deafness - surgery
Dominant
Female
Follow-Up Studies
Genetic Carrier Screening - methods
Genetic Predisposition to Disease
Genetic Testing
GJB2
Hearing loss
Hearing Loss, Sensorineural - diagnosis
Hearing Loss, Sensorineural - genetics
Hearing Loss, Sensorineural - surgery
Heterozygote
Humans
Otolaryngology
Pediatrics
Penetrance
Point Mutation
Polymerase Chain Reaction - methods
Treatment Outcome
Tunisia
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Summary:Abstract Objectives Mutations of GJB2 encoding connexin 26 are the most common cause of hearing loss. They are responsible for up to 50% of ARNSHL. The pathogenic mutations in this gene are generally inherited recessively. Dominant mutations in GJB2 also cause hearing loss, either in isolated non-syndromic form or as part of a syndrome associated with various skin disorders. Methods We screened a Tunisian child affected by congenital, bilateral, profound, sensorineural hearing loss for mutations in GJB2 gene using PCR and direct sequencing. Results The proband was found to be compound heterozygous for recessive and dominant GJB2 mutations respectively p.V37I (c.109G > A) and p.R143Q (c.428G > A). Surprisingly the hearing mother is a carrier for this dominant GJB2 mutation. This proband underwent a cochlear implant at four years old. The evaluation using APCEI and IT-MAIS tests at six months post implantation indicates a successful cochlear implant outcome since the deaf child began to acquire language abilities and auditory sensation. Conclusions The p.R143Q mutation was described for the first time in Tunisia. We confirm the low penetrance of this mutation since the proband mother is a carrier despite her normal hearing. We show the effectiveness of cochlear implant to restore the communication abilities and auditory sensation for our patient.
ISSN:0165-5876
1872-8464
DOI:10.1016/j.ijporl.2013.06.013