Post-lingual non-syndromic hearing loss phenotype: a novel homozygous missense mutation in MITF

Abstract

Background Hearing loss (HL) represents the most common congenital sensory impairment with an incidence of 1-5 per 1000 live births. Non-syndromic hearing loss (NSHL) is an isolated finding that is not part of any other disorder accounting for 70% of all genetic hearing loss cases. Methods In the current study, we report a multifactorial genetic mode of inheritance in a NSHL consanguineous family using exome sequencing technology. We evaluated the possible effects of the single nucleotide variants (SNVs) detected in our patients using in silico methods. Results Two bi-allelic SNVs were detected in the affected patients; a MYO15A (. p.V485A) variant, and a novel MITF (p.P338L) variant. Along with these homozygous mutations, we detected two heterozygous variants in well described hearing loss genes (MYO7A and MYH14). The novel p. Pro338Leu missense mutation on the MITF protein was predicted to change the protein structure and function. Conclusion The novel MITF variant is the first bi-allelic SNV in this gene to be associated with an autosomal recessive non-syndromic HL case with a post-lingual onset. Our findings highlight the importance of whole exome sequencing for a comprehensive assessment of the genetic heterogeneity of HL.