Objective: Literature review of the genetic etiology of hearing loss (HL) in the African American (AA) population.
Data sources: PubMed, EBSCO, and CINAHL were accessed from 1966 to 2018.
Review methods: PRISMA guidelines were followed. Search terms included permutations of "hearing loss," "African American," "black," and "genetic"; "African American" was then cross-referenced against documented HL genes. AA subjects included in multiethnic cohorts of genetic HL testing were identified by searching the key terms "hearing loss" and "ethnic cohort" and "genetic." The Q-Genie tool was used in the quality assessment of included studies. An allele frequency meta-analysis of pathogenic GJB2 variants in the AA population was performed and stratified by hearing status.
Results: Four hundred seventeen articles were reviewed, and 26 met our inclusion criteria. Ten studies were included in the GJB2 meta-analysis. In the general AA population, pathogenic GJB2 variants are rare, including the 35delG allele, which displayed a carrier frequency of 0.05%. Pathogenic variants were discovered in seven nonsyndromic HL genes (GJB2, MYO3A, TECTA, STRC, OTOF, MYH14, TMC1), eight syndromic HL genes, and one mitochondrial HL gene. Recent comprehensive genetic testing using custom genetic HL testing platforms has yielded only a 26% molecular diagnosis rate for HL etiologies in the AA population.
Conclusions: Investigators should be encouraged to provide an ethnic breakdown of results. Sparse literature and poor diagnosis rates indicate that genes involved in HL in the AA population have yet to be identified. Future explorative investigations using next-generation sequencing technologies, such as whole-exome sequencing, into the AA population are warranted.