Xiao-Wen Liu1, Jian-Chao Wang2, Su-Yang Wang3, Shu-Juan Li4, Yi-Ming Zhu1, Wen-Juan Ding1, Chen-Yang Xu1, Lei Duan1, Bai-Cheng Xu1, Yu-Fen Guo5. 1. Department of Otolaryngology-Head and Neck Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu, 730030, PR China. 2. Department of Otolaryngology-Head and Neck Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu, 730030, PR China; Department of Otolaryngology-Head and Neck Surgery, National Clinical Research Center for Infectious Disease, Shenzhen Third People's Hospital, The Second Affiliated Hospital, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong, 518100, PR China. 3. Department of Otolaryngology-Head and Neck Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu, 730030, PR China; Department of Otolaryngology-Head and Neck Surgery, Gansu Provincial Maternity and Child-care Hospital, Lanzhou, 730050, PR China. 4. Department of Otolaryngology-Head and Neck Surgery, Gansu Provincial Hospital, Lanzhou, Gansu, 730000, PR China. 5. Department of Otolaryngology-Head and Neck Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu, 730030, PR China; Health Commission of Gansu Province, Lanzhou, Gansu, 730000, PR China. Electronic address: gyflhmm@163.com.
Abstract
OBJECTIVE: To expose the spectrum and frequency of GJB2, GJB3, SLC26A4 and MT-RNR1 in northwest China and to investigate the underlying causative genes in patients without common mutations. METHODS: We analyzed the mutation screening results of GJB2, GJB3, SLC26A4 and MT-RNR1 in 398 unrelated severe-to-profound probands with bilateral, symmetrical sensorineural hearing loss. Subsequently, we selected 10 probands with a significant family history of inherited hearing loss (HL) that did not have the above four common gene mutations to perform next-generation sequencing (NGS) of 139 known deafness genes, followed by co-segregation analysis of all available family members. RESULTS: Among the 398 patients, 69 (17.34%) had the biallelic GJB2 gene mutations, and the most common mutations were c.235delC, c.109G>A and c.299_300delAT, with allele frequencies of 12.31%, 3.38% and 3.89%, respectively. A total of 63 (15.83%) cases with biallelic SLC26A4 mutations were detected, and the most common pathogenic alleles were c.919-2A>G, c.2168A>G and c.1174A>T, with allele frequencies of 9.17%, 2.26% and 0.88%, respectively. Mitochondrial gene mutations were detected in 9 (2.26%) patients, with 5 cases of mitochondrial DNA (mtDNA) m.1555A>G mutation and 4 cases of mtDNA m.1095T>C mutation. In 10 probands with a clear family history of HL, NGS showed two novel pathogenic variants in 2 families, including c.4129C>T/c.3268C>T in LOXHD1, c.334G>A/c.2968G>T in CDH23. Sanger sequencing confirmed that these variants segregated with the HL in each family. CONCLUSIONS: Our results showed that GJB2 and SLC26A4 were the two major HL-causing genes in northwest China. The most common mutation alleles in GJB2 were c.235delC, c.109G>A and c.299_300delAT, and those in SLC26A4 were c.919-2A>G, c.2168A>G and c.1174A>T. In addition, both genes and their loci can be used as the first selection of deafness gene screening. Additionally, for patients who did not have mutations of these common genes, NGS provided an efficient diagnosis for increasing known deafness genes.
OBJECTIVE: To expose the spectrum and frequency of GJB2, GJB3, SLC26A4 and MT-RNR1 in northwest China and to investigate the underlying causative genes in patients without common mutations. METHODS: We analyzed the mutation screening results of GJB2, GJB3, SLC26A4 and MT-RNR1 in 398 unrelated severe-to-profound probands with bilateral, symmetrical sensorineural hearing loss. Subsequently, we selected 10 probands with a significant family history of inherited hearing loss (HL) that did not have the above four common gene mutations to perform next-generation sequencing (NGS) of 139 known deafness genes, followed by co-segregation analysis of all available family members. RESULTS: Among the 398 patients, 69 (17.34%) had the biallelic GJB2 gene mutations, and the most common mutations were c.235delC, c.109G>A and c.299_300delAT, with allele frequencies of 12.31%, 3.38% and 3.89%, respectively. A total of 63 (15.83%) cases with biallelic SLC26A4 mutations were detected, and the most common pathogenic alleles were c.919-2A>G, c.2168A>G and c.1174A>T, with allele frequencies of 9.17%, 2.26% and 0.88%, respectively. Mitochondrial gene mutations were detected in 9 (2.26%) patients, with 5 cases of mitochondrial DNA (mtDNA) m.1555A>G mutation and 4 cases of mtDNA m.1095T>C mutation. In 10 probands with a clear family history of HL, NGS showed two novel pathogenic variants in 2 families, including c.4129C>T/c.3268C>T in LOXHD1, c.334G>A/c.2968G>T in CDH23. Sanger sequencing confirmed that these variants segregated with the HL in each family. CONCLUSIONS: Our results showed that GJB2 and SLC26A4 were the two major HL-causing genes in northwest China. The most common mutation alleles in GJB2 were c.235delC, c.109G>A and c.299_300delAT, and those in SLC26A4 were c.919-2A>G, c.2168A>G and c.1174A>T. In addition, both genes and their loci can be used as the first selection of deafness gene screening. Additionally, for patients who did not have mutations of these common genes, NGS provided an efficient diagnosis for increasing known deafness genes.
Authors: Samuel Mawuli Adadey; Edmond Wonkam-Tingang; Elvis Twumasi Aboagye; Daniel Wonder Nayo-Gyan; Maame Boatemaa Ansong; Osbourne Quaye; Gordon A Awandare; Ambroise Wonkam Journal: Life (Basel) Date: 2020-10-28