RESUMEN
Thus far, 13 genes for autosomal dominant hearing loss have been localized to specific chromosomal regions, but none of the genes has been cloned. Only a single family has been linked to each of these loci, with the exception of DFNA2. DFNA2 was originally mapped in two extended families originating from Indonesia and the United States. In this study we report linkage to DFNA2 in three additional large families with autosomal dominant hearing loss from Belgium and The Netherlands. These five DFNA2 families show a similar progressive sensorineural hearing loss, starting in the high frequencies and also affecting the middle and low frequencies later in life. Combining the information from all linked families, the candidate region that is most likely to contain the DFNA2 gene was reduced to a 1.25-Mb region between markers D1S432 and MYCL1. Different haplotypes segregating with the hearing loss were found in all five families, suggesting that different mutations are present in the same gene. These results indicate that DFNA2 is most likely an important gene for autosomal dominant hearing loss.