Abstract
In China, approximately 30,000 babies are born with hearing impairment each year. However, the molecular factors causing congenital hearing impairment in the Xiamen area of Fujian province have not been evaluated. To provide accurate genetic testing and counseling in the Xiamen area, we investigated the molecular etiology of non-syndromic deafness in a deaf population from Xiamen. Unrelated students with hearing impairment (n = 155) who attended Xiamen Special Education School in Fujian Province were recruited for this study. Three common deafness-related genes, GJB2, SLC26A4, and mtDNA12SrRNA, were analyzed using all-exon sequencing. GJB2 mutations were detected in 27.1% (42/155) of the entire cohort. The non-syndromic hearing loss (NSHL) hotspot mutations c.109G>A (p.V37I) and c.235delC were found in this population, whereas the Caucasian hotspot mutation c.35delG was not. The allelic frequency of the c.109G>A mutation was 9.03% (28/310), slightly higher than that of c.235delC (8.39%, 26/310), which is the most common GJB2 mutation in most areas of China. The allelic frequency of the c.109G>A mutation was significantly higher in this Xiamen’s deaf population than that in previously reported cohorts (P = 0.00). The SLC26A4 mutations were found in 16.77% (26/155) of this cohort. The most common pathogenic allele was c.IVS7-2A>G (6.13%, 19/310), and the second most common was the c.1079C>T (p.A360V) mutation (1.94%, 6/310) which has rarely been reported as a hotspot mutation in other studies. The mutation rate of mtDNA12SrRNA in this group was 3.87% (6/155), all being the m.A1555G mutation. These findings show the specificity of the common deaf gene-mutation spectrum in this area. According to this study, there were specific hotspot mutations in Xiamen deaf patients. Comprehensive sequencing analysis of the three common deaf genes can help portray the mutation spectrum and develop optimal testing strategies for deaf patients in this area.
Highlights
Hearing impairment is among the most common congenital disorders; approximately half of the cases are caused by genetic factors
The most common mutation of SLC26A4 seen in the Chinese deaf population is c.IVS7-2A>G; its detection rate can be as high as 12.5% [6,7,8]
To provide accurate genetic testing and counseling in the Xiamen area, we evaluated the molecular etiology of non-syndromic deafness in a deaf population from Xiamen Special Education School
Summary
Hearing impairment is among the most common congenital disorders; approximately half of the cases are caused by genetic factors. In China, many previous genetic screening studies have shown that GJB2, SLC26A4, and mtDNA12SrRNA are the three most common causes of nonsyndromic deafness, and the mutations in these three genes can explain 26.65–35.7% of the pathogenesis of Chinese non-syndromic hearing impairment [1,2,3]. The most common mutation of mtDNA12SrRNA is m.A1555G, the frequency of which was reported to be 3.43% in a Chinese deaf population [9]. Xiamen is a city in the South Fujian region in southern China, neighboring the Golden Gate Island of Taiwan. Because it is an island, Xiamen communicated with the mainland by boat and it was relatively isolated before the construction of Xiamen Gaoji Seawall in 1955. All exons in the open reading frames (ORF) of the GJB2, SLC26A4, and mtDNA12SrRNA genes were sequenced and analyzed
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