Feb. 10, 2011— -- It took almost 20 years, but Betti Lidsky finally found out what caused three of her four children to go blind.
Betti's two daughters and son, now in their 30s, were diagnosed with retinitis pigmentosa when they were teenagers in 1992. Retinitis pigmentosa, or RP, is a group of genetic conditions that lead to retinal degeneration and can cause severe, incurable vision problems in later adulthood. It can sometimes lead to blindness. Neither Betti nor her husband have RP, but both carried the recessive gene for it.
"It was initially very devastating," said Lidsky, who is from south Florida. "My husband cried for a year and a half."
Researchers have identified more than 50 genes associated with RP, but no one could figure out which gene caused the condition in the Lidsky children.
Finally, last spring, the family got the news they spent years hoping for: researchers at the University of Miami's John T. Macdonald Foundation Department of Human Genetics finally identified the gene responsible for RP in their family.
"It was huge news. It was monumental. For 18 years, we searched for the genetic cause," said Lidsky.
"They had their DNA tested for many candidate genes, but none of the known RP genes caused it in their family," said Margaret A. Pericak-Vance, associate dean for human genomic programs and director of the Hussman Institute for Human Genomics at the University of Miami.
Vance and her colleagues from the University of Miami, Mount Sinai School of Medicine in New York and Vanderbilt University in Nashville, Tenn. used a new DNA sequencing technique that enabled them to look at all possible variations in all genes. Older technology did not allow that kind of analysis.
"This has only been possible for the past year and a half," said Pericak-Vance. "Before, we couldn't do such a complete scan. We would have had to use multiple families to identify a gene."
Experts say the finding is very significant and can finally provide an answer after years of agonizing questions for the Lidsky family. They also say the finding could offer hope for someday finding a treatment for RP.