Making Sense of Nonsyndromic Deafness

IN 1992, León et al¹ mapped the first nonsyndromic deafness locus to chromosome 5q31 in a large kindred from Costa Rica, segregating autosomal dominant postlingual deafness that begins as a low-frequency loss at about age 10 years and progresses to involve all frequencies by age 30 years. Five years later, Lynch et al² identified a protein-truncating mutation in the causative gene HDIA1, the human homologue of the Drosophila gene diaphanous. As of September 2002, 41 dominant (DFNA + integer), 33 recessive (DFNB + integer) and 8 X-linked (DFN + integer) deafness loci have been mapped and 29 different deafness-related genes have been cloned.³