The missense mutation c.4994 T > C (p.L1665P) was assumed to be pathogenic because 1) mutations in OTOF have been reported to be the main cause of autosomal recessive non-syndromic deafness DFNB9 that associated with ANSD [11, 17]; 2) the region is highly conserved across mammalian species (Fig. 3b); 3) it was found in compound heterozygosity with p.R452X; 4) some pathogenic mutations have been found near the mutation site; and 5) no other recessive variants related to deafness could be identified by WES. This evidence concerns the gene OTOF and autosomal recessive nonsyndromic hearing loss 9.