CONCLUSIONS: p.R143Q mutation in GJB2 can cause mild to profound bilateral sensorineural hearing impairment. Although not common in Chinese patients with hearing loss, it is important to identify the specific phenotype and genotype correlations of the dominant mutation in GJB2. OBJECTIVE: Mutations in the GJB2 gene are the most common cause of nonsyndromic autosomal recessive sensorineural hearing loss. A few mutations in GJB2 have also been reported to cause dominant nonsyndromic or syndromic hearing loss. However, dominant mutation in GJB2 is not common in Chinese populations. METHODS: Three patients with hearing impairment from Chinese families are reported here. Temporal CT scan, complete physical (including skin and hair) and otoscopic examinations, and an audiological study, including tympanometry, auditory brainstem response (ABR), auditory steady-state response (ASSR), and 40 Hz auditory event-related potential (40 Hz-AERP), were carried out. The two exons of GJB2, the coding exons of SLC26A4, and mitochondrial 12S rRNA were sequenced. RESULTS: Sequencing of GJB2 in two patients showed a heterozygous c.428G>A (p.R143Q) mutation, and the third patient was identified with c.299delAT and c.428G>A compound heterozygous mutation. Sequence analysis of the coding exons of SLC26A4 and mitochondrial 12S rRNA was performed but no sequence aberration or deletion was found.
CONCLUSIONS:p.R143Q mutation in GJB2 can cause mild to profound bilateral sensorineural hearing impairment. Although not common in Chinese patients with hearing loss, it is important to identify the specific phenotype and genotype correlations of the dominant mutation in GJB2. OBJECTIVE: Mutations in the GJB2 gene are the most common cause of nonsyndromic autosomal recessive sensorineural hearing loss. A few mutations in GJB2 have also been reported to cause dominant nonsyndromic or syndromic hearing loss. However, dominant mutation in GJB2 is not common in Chinese populations. METHODS: Three patients with hearing impairment from Chinese families are reported here. Temporal CT scan, complete physical (including skin and hair) and otoscopic examinations, and an audiological study, including tympanometry, auditory brainstem response (ABR), auditory steady-state response (ASSR), and 40 Hz auditory event-related potential (40 Hz-AERP), were carried out. The two exons of GJB2, the coding exons of SLC26A4, and mitochondrial 12S rRNA were sequenced. RESULTS: Sequencing of GJB2 in two patients showed a heterozygous c.428G>A (p.R143Q) mutation, and the third patient was identified with c.299delAT and c.428G>A compound heterozygous mutation. Sequence analysis of the coding exons of SLC26A4 and mitochondrial 12S rRNA was performed but no sequence aberration or deletion was found.