Analysis of Genotypes and Clinical Phenotypes in 2,598 Patients with Non-Syndromic Deafness

WANG Fang; CHEN Xiaowan; XU Baicheng; LIU Xiaowen; ZHU Yiming; CHEN Xingjian; GUO Yufen

doi:10.3969/j.issn.1672-2922.2016.06.010

Abstract：Objective To investigate the correlation between GJB2 gene and mitochondrial DNAA1555G mutation and clinical audiology and age of onset in non-syndromic deafness. Methods GJB2 and mitochondrial DNAA1555G muta-tions were tested in 2,598 patients with non-syndrome deafness and the results analyzed. Results Hearing loss caused by GJB2 homozygous mutations was different from that caused by GJB2 compound heterozygous mutations (χ2=10.064, P=0.007). The rate of GJB2 pathogenic mutations was highest in patients with profound hearing loss (10.43%), followed by pa-tients with severe (8.81%) and moderate hearing (8.03%) (χ2=8.32, P=0.04). No GJB2 pathogenic mutation was found in pa-tients with mild hearing loss. The mtDNAA1555G detection rate showed no significant difference among patients with dif-ferent degrees of hearing loss (χ2=6.901, P=0.068). The prevalence of GJB2 pathogenic mutations was higher in patients with pre-lingual deafness (11.96%) than those with post-lingual deafness (3.83%) (χ2=13.434, P=0.000), while the preva-lence of mtDNAA1555G mutation showed no significant difference (χ2=0.089, P=0.766). The age of deafness onset was dif-ferent in patients with GJB2 mutations than those with mtDNAA1555G mutation (χ2=9.901, P=0.019). Conclusions Our study shows that hearing loss in patients with GJB2 homozygous mutations is more severe than those with compound muta-tions, and is in the profound loss category in most cases. Hearing loss in patients with mtDNAA1555G mutation is relatively mild. GJB2 mutations tend to cause pre-lingual onset deafness, while mtDNAA1555G mutation seems to affect patient of various ages.