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Scientists Discover an Important Deafness Gene Mutation
Scientists have discovered a genetic mutation that may be responsible for most nonsyndromic recessive deafness in the Ashkenazi Jewish population, according to a recent study reported in the November 19, 1998, issue of the New England Journal of Medicine.
Nonsyndromic recessive deafness accounts for approximately 80 percent of hereditary deafness. This type of deafness happens when an altered or mutated copy of a gene is inherited from each parent. Mutations of the gene GJB2, which encodes the protein connexin 26, have been implicated in nonsyndromic recessive deafness. A specific mutation called 30delG appears to be responsible for the majority of nonsyndromic recessive deafness among the Mediterranean European population.
"We found that the 30delG mutation occurs rarely in the Ashkenazi Jewish population," stated primary investigator Robert J. Morell, Ph.D., of the Laboratory of Molecular Genetics of the National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health, "whereas a different mutation, 167delT, occurs frequently." "The 167delT mutation is practically nonexistent in other populations that we examined," he added.
Dr. Morell emphasized, however, that although the 167delT mutation is prevalent in the Ashkenazi Jewish population, nonsyndromic recessive deafness occurs at about the same frequency as in the general population.
"Knowledge of this specific mutation will be an enormous help to Ashkenazi Jewish families who are seeking a better understanding of hereditary deafness," commented coinvestigator Thomas B. Friedman, Ph.D., Chief of the NIDCD's Laboratory of Molecular Genetics.
"In addition, knowledge of this mutation can help identify hearing impairment at birth so that educational programs that stimulate language can begin immediately," said NIDCD Director James F. Battey, Jr., M.D., Ph.D.
This study was a collaborative effort among scientists in Dr. Friedman's laboratory and scientists from the Kresge Hearing Research Laboratory, Louisiana State University Medical Center, New Orleans; Michigan State University, East Lansing; University of Antwerp, Antwerp, Belgium; and New York University Medical Center, New York.
As the nation's focal point for research in human communication, the NIDCD conducts and supports biomedical and behavioral research and research training on normal mechanisms as well as diseases and disorders of hearing, balance, smell, taste, voice, speech and language that affect millions of Americans.