2.7. Heritability of the metabolic syndrome

Genetic heritability of the insulin resistance trait would serve as an indicator of insulin resistance as the primary defect in the metabolic syndrome. In a polygenic model, the estimated heritability of BMI was 80%, whereas the WH ratio seemed to be influenced mainly by the environment (i.e. the Western life-style with a high fat intake and low levels of physical activity, heritability 6%). Fasting plasma insulin had a heritability of 26% and 30 min OGTT plasma insulin 50% (Poulsen et al. 1999), showing the overall genetic contribution to insulin resistance to be of the order of 40%. Therefore, environmental factors predominate in the development of insulin resistance in genetically susceptible individuals (Beck-Nielsen and The European Group for the Study of Insulin Resistance (EGIR) (1999).