Congenital hearing loss: a literature review of the genetic etiology in a Mexican population

Abstract

Hearing loss is the most frequent sensory disorder, with an incidence of 1:1500 live newborns. In more than 50% of patients, it is associated with a genetic cause, while in up to 30% of cases, it is related to syndromic entities. We performed a literature review of studies on congenital hearing loss of genetic origin in the Mexican population. We identified eight reports that showed that the pathogenic variants most frequently associated with hearing loss are related to the GJB2 gene, although in a low percentage (3%). Other mutations were identified in the GJB6, SLC26A4, or CHD23 genes. On this basis, a possible diagnostic strategy in Mexican patients with hearing loss is to consider an initial screening of these three genes. If these genes were negative for pathogenic variants, the following steps would be to consider second-generation sequencing analysis focused on panels of genes associated with hearing loss, isolated or syndromic, and if necessary, to perform exome or whole-genome analysis. Establishing an etiologic cause is critical in clinically evaluating patients with congenital hearing loss and their families. It can help determine rehabilitation strategies, such as hearing aids or cochlear implants and provide information on disease progression and genetic counseling in this population.

Insight into the Natural History of Pathogenic Variant c.919-2A>G in the SLC26A4 Gene Involved in Hearing Loss: The Evidence for Its Common Origin in Southern Siberia (Russia)

“…In addition, if the required information was not available, we calculated ourselves the proportion of alleles carrying c.919-2A>G among all mutant SLC26A4 alleles identified in patients. Based on the obtained data, we came to the conclusion that the spatial distribution of c.919-2A>G can be limited to the territory of Eurasia, since c.919-2A>G was not found on other world continents, as follows from the relevant studies [ 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ]. Figure 2 represents a hot map demonstrating the c.919-2A>G prevalence in patients with SLC26A4 -related hearing loss in Eurasia.…”

High prevalence of syndromic hearing loss in Mexican children undergoing cochlear implantation

“…Prior studies of genetic hearing loss in Mexican children with SNHL have been small and focused on single‐gene testing. The diagnostic strategy recommended in some CI centers in Mexico is to screen GJB2, SLC26A4 , and CHD23 genes; additional genetic analyses are explored only if initial screening is nondiagnostic 16 . There remains a lack of access to genetic testing even when the patient has a clearly syndromic clinical presentation and when genetic diagnosis may directly inform care.…”

“…The diagnostic strategy recommended in some CI centers in Mexico is to screen GJB2, SLC26A4, and CHD23 genes; additional genetic analyses are explored only if initial screening is nondiagnostic. 16 There remains a lack of access to genetic testing even when the patient has a clearly syndromic clinical presentation and when genetic diagnosis may directly inform care. These patients may have tested through a private lab for a fee or through a research study.…”