The c.242G>A mutation in LRTOMT gene is responsible for a high prevalence of deafness in the Moroccan population.

Congenital hearing impairment (HI) affects one in 1,000 newborns and has a genetic cause in 50 % of the cases. Autosomal recessive non-syndromic hearing impairment is responsible for 70-80 % of all hereditary cases of HI. Recently, it has been demonstrated that, mutations of LRTOMT are associated with profound nonsyndromic hearing impairment at the DFNB63 locus. The objective of this study is to evaluate the carrier frequency of c.242G>A mutation in LRTOMT gene and define the contribution of this gene in the etiology of deafness in Moroccan population. We screened 105 unrelated Moroccan families with non-syndromic HI and 120 control individuals for mutation in the exon 8 of the LRTOMT gene, by sequencing and PCR-RFLP. The Homozygous c.242G>A mutation was found in 8.75 % of the families tested and in 4.16 % of control in the heterozygous state. Our results show that after the GJB2 gene mutation in LRTOMT gene is the second cause of congenital hearing impairment in Moroccan patients. This finding should facilitate diagnosis of congenital deafness of the affected subjects in Morocco.