Connexin26 mutations associated with nonsyndromic hearing loss

Area of Science:

• Genetics
• Audiology
• Molecular Biology

Background:

• Mutations in the GJB2 gene, encoding connexin26 (Cx26), are a primary cause of congenital deafness.
• The 35delG mutation is prevalent in white populations, while other mutations like 167delT and R143W are found in specific ethnic groups.
• Understanding Cx26 mutations in diverse populations is crucial for diagnosing and managing nonsyndromic hearing loss (NSHL).

Purpose of the Study:

• To investigate the spectrum and frequency of connexin26 (Cx26) mutations in Korean patients with nonsyndromic hearing loss (NSHL) and newborns.
• To compare mutation profiles between patient and newborn cohorts to identify disease-causing variants.
• To determine the ethnic-specific mutation patterns of Cx26 in the Korean population.

Main Methods:

• Prospective study including 147 unrelated patients with congenital NSHL and 100 audiologically screened newborns.
• Direct sequencing of the GJB2 gene (encoding Cx26) in both directions for all participants.
• Analysis of mutation frequencies and types, including familial segregation studies for identified mutations.

Main Results:

• Thirteen distinct Cx26 mutations were identified in the Korean cohort.
• The 235delC mutation was significantly more frequent in NSHL patients (5%) compared to newborns (0.5%).
• The 35delG mutation, common in other populations, was rarely detected in both Korean groups. Polymorphic variants V27I and E114G were common.

Conclusions:

• The 235delC mutation is a significant cause of autosomal recessive NSHL in the Korean population.
• Cx26 mutation profiles vary considerably across different ethnic backgrounds.
• These findings highlight the importance of ethnic-specific genetic screening for congenital deafness.