Hearing loss in Africa: current genetic profile

Abstract

Hearing impairment (HI) is highly heterogeneous with over 123 associated genes reported to date, mostly from studies among Europeans and Asians. Here, we performed a systematic review of literature on the genetic profile of HI in Africa. The study protocol was registered on PROSPERO, International Prospective Register of Systematic Reviews with the registration number “CRD42021240852”. Literature search was conducted on PubMed, Scopus, Africa-Wide Information, and Web of Science databases. A total of 89 full-text records was selected and retrieved for data extraction and analyses. We found reports from only 17/54 (31.5%) African countries. The majority (61/89; 68.5%) of articles were from North Africa, with few reports found from sub-Saharan Africa. The most common method used in these publications was targeted gene sequencing (n = 66/111; 59.5%), and only 13.5% (n = 15/111) used whole-exome sequencing. More than half of the studies were performed in families segregating HI (n = 51/89). GJB2 was the most investigated gene, with GJB2: p.(R143W) founder variant only reported in Ghana, while GJB2: c.35delG was common in North African countries. Variants in MYO15A were the second frequently reported in both North and Central Africa, followed by ATP6V1B1 only reported from North Africa. Usher syndrome was the main syndromic HI molecularly investigated, with variants in five genes reported: USH2A, USH1G, USH1C, MYO7A, and PCDH15. MYO7A: p.(P1780S) founder variant was reported as the common Usher syndrome variant among Black South Africans. This review provides the most comprehensive data on HI gene variants in the largely under-investigated African populations. Future exomes studies particularly in multiplex families will likely provide opportunities for the discovery of the next sets of novel HI genes, and well as unreported variants in known genes to further our understanding of HI pathobiology, globally.

An overload of missense variants in the OTOG gene may drive a higher prevalence of familial Meniere disease in the European population

“…The reported differences in the FMD prevalence may be due to differences in the genetic structure of each population. More frequent and founder variants in hearing impairment genes have already been described in European, African, Asian, and American populations (Aboagye et al 2023 ; Adadey et al 2022 ); therefore, finding founder variants in specific genes that cause FMD would not be surprising. Founder variants are those variants found with a high frequency within a particular population caused by the presence of the variant in an ancestor or small group of ancestors (Jain et al 2021 ).…”

An overload of missense variants in the OTOG gene may drive a higher prevalence of familial Meniere disease in the European descendant population

“…The reported differences in the FMD prevalence may be due to differences in the genetic structure of each population. More frequent and founder variants in hearing impairment genes have already been described in European, African, Asian, and American populations (14,35), therefore, nding founder variants in speci c genes that cause FMD would not be surprising. Founder variants are those pathogenic variants found with a high frequency within a particular population caused by the presence of the variant in an ancestor or small group of ancestors (36).…”

Renal tubular acidosis as one of the causes of urolithiasis.

“…Опубликованы работы, в которых сообщается, что мутации гена ATP6V1B1 могут проявляться фенотипически также в виде тугоухости и нарушений слуха [38]. Исходя из собственного клинического опыта, можем сказать, что в клинической практике встречаются пациенты с врожденной наследственной тугоухостью и рецидивирующим течением уролитиаза.…”