The presence of a genetic variation in the DNA of mitochondria may increase a person's risk of developing age-related macular degeneration (AMD), a new study by researchers at Vanderbilt University Medical Centre has revealed.
The researchers focused their study on a particular variation in the mitochondrial genome associated with the disease that occurs in about 10 percent of Caucasians, referred to as mitochondrial haplogroup T.
"Most people don't realize that we have two genomes. We have the nuclear genome - the "human genome" - that makes the cover of all the magazines, and then we also have this tiny genome in mitochondria in every cell," said lead author Dr Jeff Canter, M.P.H., an investigator in the Centre for Human Genetics Research.
"We suspect that this variant will be one of a small group of important genetic variations that underlie AMD. By knowing this, we have a better chance of predicting accurately who will get the disease," he added.
AMD is a condition that affects sharp central vision necessary for everyday activities like reading, driving, watching television, and identifying faces.
A team led by Jonathan Haines, Ph.D and director of the Center for Human Genetics Research had identified a variant in the Complement Factor H (CFH) gene as accounting for up to 43 percent of AMD. Variations in ApoE2 and a gene called LOC387715 on chromosome 10 have also been linked to the disease. They also demonstrated an interaction between the chromosome 10 gene and smoking in raising AMD risk.
The present study including Canter, Haines and Paul Sternberg, also examined variation in these nuclear genes in 280 cases and 280 age-matched controls, and demonstrated that the mitochondrial genome variation was independent of the known nuclear factors.
"We're at the stage where we can use genetic information to predict who is likely to develop AMD well before they actually develop it. Now we can conduct trials of preventive treatments - something's that never been possible before," said Haines.
Sternberg, G.W. Hale Professor and Chairman of the Vanderbilt Eye Institute is currently also leading a trial to test preventive measures in AMD.
"By identifying genetic changes associated with the mitochondria, our results lend additional confirmatory evidence for the role of oxidative stress in AMD. This supports study of interventions that attempt to bolster our antioxidant defenses," said Sternberg.
The study appears in the journal PLoS ONE.