Nonsyndromic Deafness DFNA1 Associated with Mutation of a Human Homolog of the <i>Drosophila</i> Gene <i>diaphanous</i>

The gene responsible for autosomal dominant, fully penetrant, nonsyndromic sensorineural progressive hearing loss in a large Costa Rican kindred was previously localized to chromosome 5q31 and named DFNA1 . Deafness in the family is associated with a protein-truncating mutation in a human homolog of the Drosophila gene diaphanous . The truncation is caused by a single nucleotide substitution in a splice donor, leading to a four–base pair insertion in messenger RNA and a frameshift. The diaphanous protein is a profilin ligand and target of Rho that regulates polymerization of actin, the major component of the cytoskeleton of hair cells of the inner ear.