Genetics of blindness being explored by McGill researchers

Montreal, QC October 9, 2003 Treatment for the most common inherited cause of blindness, retinitis pigmentosa, is one step closer, according to investigators at the Research Institute of the McGill University Health Centre (MUHC). They are the first to link two new gene mutations in two French-Canadian families to loss of vision in humans. Their findings are published in this month’s issue of the American Journal of Ophthalmology. This project was funded by the Canadian Institutes of Health Research (CIHR), le Fonds de la recherche en sant du Qubec (FRSQ) and the Foundation Fighting Blindness – Canada.

Approximately 1.5 million people worldwide are affected by retinitis pigmentosa, which at the moment has no cure. This disease causes vision loss by progressive degeneration and death of the cells that make up the retina, the portion of the eye that responds to light.

“Retinitis pigmentosa is a devastating and complex disease,” says Dr Robert Koenekoop, principal investigator and director of pediatric ophthalmology at the Montreal Children’s Hospital of the MUHC. “Many genes, gene mutations and symptoms are involved. The first steps to developing a treatment are the characterization of all these factors. Important progress has been made by identifying two important gene mutations present in the French-Canadian population.”

Dr Koenekoop, in collaboration with MUHC geneticist, Dr Guy Rouleau, examined two very large French-Canadian families afflicted with retinitis pigmentosa for four generations. Ophthalmic evaluations and genetic analysis were used to characterize the gene mutations and the resulting phenotype. They demonstrated that these mutations resulted in variable, severe forms of the disease and in some cases other neurological disorders, such as hearing loss.

“Our findings show that different gene mutations result in different symptoms of the disease,” says Dr Rouleau. “Our study will provide hope to those families who have suffered from this disease for generations and will lead to new screening and diagnostic tests.”