Pat Phalin learned she had hearing loss at 30 when she volunteered to give hearing tests at her local school. The pupils heard sounds she could not hear.
Her husband Larry, a genealogy enthusiast, saw a pattern in his wife’s family history. Her mother, grandfather and great-grandfather had severe hearing loss as adults. One of the Phalins’ children had hearing problems before he reached school age.
The hearing loss must be hereditary, Larry Phalin thought, though his wife’s family didn’t seem to realize it. “They blamed it on everything else under the sun: They worked in loud factories, they listened to loud music. One got hit by a tractor,” he says.
Phalin, who lives near Chicago, heard 14 years ago that scientists were seeking families for studies of hereditary hearing loss. He got in touch with Dr. Marci Lesperance, now a hearing researcher at the U-M Health System.
That contact sent Lesperance and her colleagues on a decade-long search. In 2001 her lab identified chromosome 12 as the one containing the responsible gene. After considering dozens of genes on this chromosome that could possibly play a role, they were able to identify one mutation that explains a previously unknown form of hereditary hearing loss.
In results published online in the American Journal of Hearing Genetics, Lesperance and researchers in Iowa, France and Germany report they have identified a mutation in a gene, SLC17A8, that accounts for a form of hearing loss that diminishes one’s ability to perceive high-frequency sounds. The severity of the mutation’s effects varies among individuals. The loss may occur early or later in life.
The researchers show that the mutation accounts for hearing loss in the Phalin family and another unrelated extended family in Iowa. Since the exact mutation occurs in two families that appear completely unrelated, the mutation may be an ancient one and not particularly rare. Future research may find that it affects others who have an unexplained family history of hearing loss, says Lesperance, an associate professor of pediatric otolaryngology at the Medical School.
The form of deafness, which the researchers have named DFNA25, also is of interest for further research because it closely resembles the hearing loss common in people as they age, called presbycusis.
Lesperance hopes the research will encourage families and physicians to be alert to the possibility that hearing problems are inherited. That may spur more people to take prompt action such as frequent hearing tests in the young and early use of hearing aids, as well as genetic counseling to understand the chances of occurrence in future children.
Larry Phalin says that he’s going to urge family members to be tested for the SLC17A8 mutation — an option that now exists for them as a result of the study.
“Then you can be prepared for it,” he says. “You can have children tested early, so they don’t have speech or school problems.”
