Custom Next‐Generation Sequencing Identifies Novel Mutations Expanding the Molecular and clinical spectrum of isolated Hearing Impairment or along with defects of the retina, the thyroid, and the kidneys

Abstract

Background In the Tunisian population, the molecular analysis of hearing impairment remains based on conventional approaches, which makes the task laborious and enormously expensive. Exploration of the etiology of Hearing Impairment and the early diagnosis of causal mutations by next‐generation sequencing help significantly alleviate social and economic problems. Methods We elaborated a custom SureSelectQXT panel for next‐generation sequencing of the coding sequences of 42 genes involved in isolated hearing impairment or along with defects of the retina, the thyroid, and the kidneys. Results We report eight pathogenic variants, four of which are novel in patients with isolated hearing impairment, hearing impairment, and renal tubular acidosis, Usher syndrome and Pendred syndrome. Functional studies using molecular modeling showed the severe impact of the novel missense mutations on the concerned proteins. Basically, we identified mutations in nuclear as well as mitochondrial genes in a Tunisian family with isolated hearing impairment, which explains definitely the phenotype detected since 2006. Conclusion Our results expanded the mutation spectrum and genotype‒phenotype correlation of isolated and syndromic hearing loss and also emphasized the importance of combining both targeted next‐generation sequencing and detailed clinical evaluation to elaborate a more accurate diagnosis for hearing impairment and related phenotypes especially in North African populations.

The genetic landscape of inherited retinal dystrophies in Arabs

“…Whereas many conditions such as CCRD, Joubert syndrome, LCA, RCD, and USHER syndrome had a wide distribution, others were restricted. For example, till today ARB cases were only reported in Lebanon [ 12 ], and non-syndromic hearing loss was only reported in KSA [ 13 ] and Tunisia [ 14 ]. However, this conclusion relies should be taken with caution as it relies on a very limited sample size.…”