A Mutational Analysis of GJB2 , SLC26A4 , MT-RNA1 , and GJB3 in Children with Nonsyndromic Hearing Loss in the Henan Province of China

BACKGROUND: Hearing impairment is one of the most common neurosensory disorders afflicting humans. Approximately half of all cases have a genetic etiology. The distribution and frequency of genetic mutations that cause deafness differ significantly by ethnic group and geographic region. METHODS: 130 sporadic nonsyndromic hearing loss (NSHL) children from the Henan province were subjected to microarray-based mutation detection. Nine pathogenic mutations were detected in four of the most common deafness-related genes (GJB2, GJB3, SLC26A4, and MT-RNA1). RESULTS: Fifty percent of the analyzed patients (65/130) were shown to have genetic defects known to be related to deafness. Slightly >30% (41/130) had biallelic pathogenic mutations. One patient had pathogenic mutations in their mitochondrial genes (MT-RNA1); no mutations were detected in the GJB3 gene. Twenty-three (17.69%) patients were carriers of a single mutation in a recessive gene; these findings alone, however, cannot be interpreted as a cause of hearing loss. Utilizing this molecular strategy, we were able to arrive at a conclusive diagnosis for 42 of the NSHL children. CONCLUSION: Genetic factors play a major role in sporadic NSHL patients from the Henan province, but it is clear that our screen needs to be expanded to include additional genes and alleles. Screening of potential pathogenic genes is important for patient risk assessment.