['To use clinical and genetic analyses to determine the mutation causing autosomal recessive nonsyndromic hearing loss (ARNSHL) segregating in two consanguineous Iranian families.', 'Family study.', 'Members of each family received otologic and audiometric examination for the type and extent of hearing loss. Linkage mapping using Affymetrix 50K GeneChips and short tandem repeat (STRP) analysis localized the hearing loss in both families to the DFNB3 locus. Direct sequencing of the MYO15A gene was completed on affected members of both families.', 'Family L-3165 segregated a novel homozygous missense mutation (c.6371G>A) that results in a p.R2124Q amino acid substitution in the myosin XVa protein, while family L-896 segregated a novel homozygous missense (c.6555C>T) mutation resulting in a p.P2073S amino acid change.'] Are mutations in the first MyTH4 domain of MYO15A a common cause of DFNB3 hearing loss?