Variations in the Mutational Spectrum in Nonsyndromic Hearing Impairment: A study of the Special Schools for the Deaf in Southern China.

OBJECTIVES

To explore the characteristics of variations in patients with nonsyndromic hearing impairment (NSHI) in Southern China to supply a theoretical basis for screening, intervention, and prevention.

MATERIALS AND METHODS

A total of 634 hearing-impaired students from the special schools for the deaf and 220 normal-hearing individuals in South China were tested using an allele-specific polymerase chain reaction-based universal array, and the screened SLC26A4 mutation carrier was examined using computed tomography. The pathogenesis of deafness was analyzed using pathography and objective hearing tests.

RESULTS

In total, 151 patients with NSHI carried pathogenic mutations in the screening chip, and the carrier rate was 23.82% (151/634) in the studied population. Of the 151 screened carriers, 65 (10.25%) patients harbored homozygous or homoplasmy mutated genes associated with autosomal recessive hearing loss; 36 (5.68%) patients with mutant alleles were homozygous for the GJB2 c.235delC mutation and 27 (4.26%) were heterozygous. Furthermore, 18 (2.84%) patients were homozygous with mutant alleles for the SLC26A4 c.919-2A>G mutation and 43 (6.78%) were heterozygous; 7 (1.10%) patients were homoplasmy mutation carriers of MT-RNR1 gene. There was 1 SLC26A4 c.919-2A>G and 1 GJB2 c.235delC heterozygous mutant allele in the group of 220 normal-hearing individuals.

CONCLUSION

GJB2 and SLC26A4 were much more prevalent than MT-RNR1 and GJB3 in South China according to this gene chip. Minuscule differences in the mutation spectrum or prevalence of GJB2 c.235delC and SLC26A4 c.919-2A>G were found in our study; furthermore, a relatively high incidence of variations was observed among these individuals with NSHI.