A team led by geneticist Dr. Karen Avraham of Tel Aviv University has discovered a defective gene that causes progressive hearing loss in a large Israeli family.
Rapid advances in genetics enabled Avraham's group, in collaboration with Dr. Mary-Claire King and Dr. Eric Lynch at University of Washington in Seattle and Dr. Robert Morell and Dr. Thomas Friedman* at the National Institute on Deafness and Other Communication Disorders (part of the National Institutes of Health), to pinpoint the location of this gene in only a year.
The discovery is reported in the March 20 issue of the journal Science.
Oz Vahava, a graduate student in Avraham's laboratory, initiated the study of the genetics of deafness in a number of generations of the Israeli family. Hearing impairment was traced back five generations to an ancestor born in 1843 in Libya. The family migrated through Tunisia and Egypt, eventually settling in Israel. The researchers identified 12 living family members with progressive hearing loss, and 11 unaffected relatives older than age 40.
Vahava determined the chromosomal location of the defective gene, named DFNA15. It was located on chromosome 5 near another gene for inherited deafness identified by King and Lynch in an extended Costa Rican family only a few months earlier (reported in the Nov. 14, 1997 issue of Science). Avraham contacted the UW geneticists, and the groups began working together.
The investigators took advantage of a shortcut revealed by a mouse. One method for identifying human genes is to examine comparable human and mouse chromosomal regions, searching for genes already known to cause problems in mice similar to those of concern in the human families.
Although the evolutionary paths of mice and humans diverged millions of
years ago, segments of their chromosomes contain the same genes. The comparison
led the geneticists to a mouse gene known to be crucial for
Contact: Laurie McHale
University of Washington