High Body Mass Index Increase the Genetic Risk of AMD
Jul 1, 2006 - 5:40:37 PM
Current cigarette smoking was associated with a fivefold increased risk and high BMI (30 or higher) was associated with a twofold higher risk of AMD. The homozygous risk genotype (CC) plus smoking conferred a tenfold higher risk of AMD, compared with non-smokers with the non-risk (TT) genotype, while the risk genotype plus higher BMI increased risk of AMD almost sixfold. Gene plus environment risk scores provided an area under the receiver operating characteristic (ROC) curve of 0.70-0.75. The attributable risks for the combination of genes and environment were 69% to 73%.
Subjects in this study were Caucasians who had either advanced AMD (574 people) or no evidence of AMD (280 individuals), based on ocular examination and ocular photographs. DNA samples were obtained from the genetic repository of the Age-Related Eye Disease Study, a National Institutes of Health (NIH) clinical trial for which Johanna M. Seddon, M.D., director of the Epidemiology Unit at MEEI and an associate professor of ophthalmology at Harvard Medical School, was clinic director at MEEI. DNA samples were genotyped at the Broad Institute Center for Genotyping and Analysis, Boston, Mass. and statistical analyses were done in the Epidemiology Unit at MEEI.
These findings convey an important message. Although we cannot change our genotype, we can alter or modify our risk of getting AMD by controlling our weight and not smoking, said Dr. Seddon. There is no question that genetic factors play an important role in this disease. However, individuals with the risk genotype may be more motivated to adhere to healthy lifestyles such as not smoking, maintaining a normal weight, getting exercise, eating an antioxidant rich diet, as well as fish, and getting exercise.
AMD is the leading cause of irreversible visual impairment and blindness among persons aged 60 and older. With the elderly population steadily growing, the burden related to this loss of visual function will increase. Limited treatment options exist for the late stages of the disease and prevention remains a promising approach for addressing this public health concern.
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