Why can't genetic tests predict certain diseases, like type 2 diabetes?
Answers
Answer:
Explanation:
The early identification of individuals at risk for type 2 diabetes (T2D) enables prevention. Recent genome-wide association studies (GWAS) have added at least 40 genetic variants to the list of already well characterized T2D risk predictors, including family history, obesity, and elevated fasting plasma glucose levels. Although these variants can significantly predict T2D alone and as a part of genotype risk scores, they do not yet offer clinical discrimination beyond that achieved with common clinical measurements. Future progress on at least two research fronts may improve the predictive performance of genotype information. First, expanded GWAS efforts in non-European populations will allow targeted sequencing of risk loci and the identification of true causal variants. Second, studies with longer prediction time horizons may demonstrate that genotype information performs better than clinical risk predictors over a longer period of the life course. At present, however, genetic testing cannot be recommended for clinical T2D risk prediction in adults.
Keywords: type 2 diabetes genetics, risk prediction models, genotype risk scores
Answer:
★ The researchers looked at risk factors — both genetic and environmental — for three common, chronic diseases, breast cancer, Type 2 diabetes and rheumatoid arthritis. All conditions are known to be influenced by some genetic and some lifestyle factors.
★ For breast cancer, the scientists created a simulation that included 15 common genetic variants associated with increased risk of the disease, along with environmental factors, such as a woman’s age at first period, age when she gave birth to her first child and the number of close relatives affected by breast cancer.
★ For Type 2 diabetes, researchers included 31 genetic variants, as well as lifestyle factors like obesity, physical activity, smoking status and family history of diabetes.
★ For rheumatoid arthritis, they considered 31 genetic variants and two major lifestyle risk factors — smoking and breast-feeding.