TUESDAY, Jan. 9 (HealthDay News) -- A combination of certain lifestyle factors and genetics can increase the risk of age-related macular degeneration (AMD), a new study says.

AMD can cause blindness and is known to have both genetic and environmental risk factors. Previous research found that a mutation in the gene for complement factor H (CFH) and a mutation in the gene LOC387715 are associated with AMD.

In the new study, researchers at Brigham and Women's Hospital and Harvard Medical School in Boston compared 457 men and women with AMD to 1,071 people without the eye disease.

Overall, people with two mutated copies of CFH and LOC387715 were 50 times more likely to develop age-related macular degeneration than those with two normal copies of each gene.

The results are published in the January issue of the journal Archives of Ophthalmology.

The study also found that non-obese people with two mutant copies of the CFH gene were four times more likely to develop AMD than non-obese people with two normal copies of the CFH gene. If people with two mutant copies of the CFH gene smoked, their risk for AMD was 8.69 times greater than nonsmokers with two normal copies of CFH. Obese people with two mutant copies of CFH were 12 times more likely to develop AMD than non-obese people with normal copies of CFH.

Nonsmokers with two mutated copies of LOC387715 were 6.3 times more likely to develop AMD than nonsmokers with normal copies of the gene. Smokers with two mutated copies of that gene were 22.47 times more likely to develop AMD than nonsmokers with two mutated copies of LOC387715.

"Elucidation of these modifying risk factors may increase understanding of disease pathogenesis and suggest lifestyle changes that may prevent AMD or delay the disease onset in carriers of predisposing genetic variants," the study authors wrote.

Other lifestyle risk factors for AMD -- such as regular aspirin use, fruit intake, fatty acid ratios and alcohol consumption -- did not seem to interact with the genetic risk factors, the researchers said.

More information

The U.S. National Eye Institute has more about AMD.