Dutch researchers have identified a common genetic variant as a cause of deafness, and they say it could be a good target for gene therapy.

Deafness in adults is known to be inherited but, unlike childhood deafness, the genetic causes aren't clear.

To date, 118 genes have been linked to deafness. Variants in these genes explain much of the deafness present at birth and in childhood, but not adult deafness — even though up to 70% of hearing loss in adults is thought to be inherited.

Researchers previously pinpointed the chromosomal region involved in one family's hearing loss, but not the gene involved.

To explore this further, they sequenced the genes of this family and 11 others affected by hearing loss — 200 people in all.

A missing section of the RIPOR2 gene was found in 20 of the 23 members of the original family. The variant was also found in three other family members, ages 23, 40 and 51, who didn't have any hearing loss.

Among the other 11 families, the same gene variant was found in 39 of 40 people with confirmed hearing loss. It was also found in two people, ages 49 and 50, who didn't have hearing loss.

The gene variant was also found in 18 of 22,952 randomly selected people for whom no information on hearing loss was available. The findings were recently published online in the Journal of Medical Genetics.

Researchers estimate that in the Netherlands and northern Europe, this genetic variant is present in more than 43,000 individuals who, therefore, either have hearing loss or are at risk for developing it.

"Because of the large number of subjects estimated to be at risk for [hearing loss] due to the c.1696_1707 del RIPOR2 variant, it is an attractive target for the development of a genetic therapy," the researchers concluded.

Hannie Kremer led the study. She's affiliated with the Department of Otorhinolaryngology and Human Genetics at Radboudumc, a university medical center in Nijmegen, Netherlands.