Scientists have found a gene that appears to play a key role in a rare and crippling disease in which babies are born deaf and have poorly developed kidneys. The find, described in the February issue of Nature Genetics, could eventually lead to a genetic test for Branchio-oto-renal (BOR) syndrome, which occurs in one in 10,000 births and accounts for 2% of cases of childhood deafness.
Geneticist Christine Petit and her colleagues at the Pasteur Institute in Paris examined DNA from 42 adults with BOR. They found a gene on chromosome 8, which they dubbed EYA1, that was severely damaged or mutated in all the people. They then tracked down a similar gene in mice that in embryos is expressed in high levels in the ear and in cells that surround and shape the developing kidney. The group now hopes to engineer a breed of mouse that lacks the gene to see if offspring develop symptoms resembling BOR. Petit speculates that EYA1 mutations in people suppress the production of the EYA1 protein, leading to the developmental defects.
The gene's apparently crucial role in embryonic development "is remarkable," says William Kimberling, a geneticist at Creighton Medical School in Omaha, Nebraska, who studies children with BOR. But EYA1 may not be the whole story, he cautions. Indeed, Petit's group has discovered in people two potential candidates--EYA2 and EYA3--whose structure is similar to EYA1. "We hypothesize that the two other genes are also involved in developmental defects," Petit says. "But presently, we don't know."