Genetic frequencies related to severe or profound sensorineural hearing loss in Inner Mongolia Autonomous Region

Abstract

The aim was to study the frequencies of common deafness-related mutations and their contribution to hearing loss in different regions of Inner Mongolia. A total of 738 deaf children were recruited from five different ethnic groups of Inner Mongolia, including Han Chinese (n=486), Mongolian (n=216), Manchurian (n=24), Hui (n=6) and Daur (n=6). Nine common mutations in four genes (GJB2, SLC26A4, GJB3 and mitochondrial MT-RNR1 gene) were detected by allele-specific PCR and universal array. At least one mutated allele was detected in 282 patients. Pathogenic mutations were detected in 168 patients: 114 were homozygotes and 54 were compound heterozygotes. The 114 patients were carriers of only one mutated allele. The frequency of GJB2 variants in Han Chinese (21.0%) was higher than that in Mongolians (16.7%), but not significantly different. On the other hand, the frequency of SLC26A4 variants in Han Chinese (14.8%) was lower than that in Mongolians (19.4%), but also not significantly different. The frequency of patients with pathogenic mutations was different in Ulanqab (21.4%), Xilingol (40.0%), Chifeng (40.0%), Hulunbeier (30.0%), Hohhot (26.3%), and in Baotou (0%). In conclusion, the frequency of mutated alleles in deafness-related genes did not differ between Han Chinese and Mongolians. However, differences in the distribution of common deafness-related mutations were found among the investigated areas of Inner Mongolia.

Unique spectra of deafness-associated mutations in Mongolians provide insights into the genetic relationships among Eurasian populations

“…Liu et al screened nine common mutations of GJB2 , SLC26A4 , MT-RNR1 , and GJB3 in 738 deaf children recruited from the Inner Mongolia region of China, including 216 Mongolians. The authors also reported a higher prevalence of SLC26A4 mutations than that of GJB2 mutations [25]. In contrast to these previous reports, our study showed that GJB2 mutations are more prevalent than SLC26A4 mutations in Mongolian patients with SNHI.…”

“…The genetics of SNHI in the Mongolian population have been documented in several previous studies [23–26]. However, most of these studies were conducted in cohorts recruited from the Inner Mongolia region of China; only limited numbers of Mongolian patients were included in these studies, and the admixture of other ethnic populations could not be excluded because of inter-population marriage [23–25]. Hearing-impaired patients from Mongolia have been the subject of only one previous study [26].…”

High Rates of Three Common GJB2 Mutations c.516G>C, c.-23+1G>A, c.235delC in Deaf Patients from Southern Siberia Are Due to the Founder Effect

“…Taking into account the complexity of ethnic history of Tuvinians, it remains unclear, who actually were the c.516G>C founders—different ancient Turkic- or Mongolic-speaking groups or other aboriginal peoples who lived there. The introduction of c.516G>C into Tuva territory with migration flows of ancient Mongolic-speaking groups is not consistent with the finding of c.516G>C in only one deaf patient from Mongolia [ 14 , 59 ] as well as with its absence in Mongolian patients living in China [ 60 , 61 ]. It is known that several nomadic Tuvinian groups roamed in the past across the territories of Tuva and Mongolia had remained in Mongolia when Tuva was separated from Mongolia to become under Russian protectorate after the breakup of the Qing Empire in 1911–1912 [ 54 , 55 ].…”

Recurrent variants in OTOF are significant contributors to prelingual nonsydromic hearing loss in Saudi patients

“…In addition, several cohort studies identify GJB2 as the most common contributor to severe to profound hearing loss, responsible for ~17–50% of severe to profound cases from various ethnic populations. 14 , 22 , 23 In our cohort, no GJB2 -sequencing variants were identified, and only one case was caused by the DFNB1 deletion. The low contribution of GJB2 is consistent with other studies of Saudi hearing-loss cohorts.…”

“… 5 , 12 The SLC26A4 and MYO7A genes, which were responsible for hearing loss in three families each, are also common contributors across ethnically diverse prelingual SNHL cohorts. 14 , 20 , 22 Variants in the STRC gene, which harbors common pathogenic large deletions in Caucasians and neighboring Middle Eastern populations, 3 were not identified. This is as expected, given that the majority of hearing loss due to variants in STRC is in the mild to moderate range.…”