Insulin Resistance and Metabolic Syndrome

Metabolic syndrome (MS) is a common disorder that affects 25% of the American population. MS is characterized by obesity, hyperglycemia, hypertriglyceridemia, low HDL cholesterol levels, and hypertension. In general, MS is the result of insulin resistance and is linked to the pathogenesis of type 2 diabetes and cardiovascular disease (CVD). Genetic factors play important roles in the pathogenesis of MS and its endophenotypes. Ample studies have been carried out to dissect the genetics of MS, including hundreds of genome scans, animal quantitative trait loci (QTLs), and association studies. Like in other complex traits, gene–gene and gene–environment interactions, low penetrance, and genetic heterogeneity have made the MS gene hunting very challenging; on the other hand, factor analyses, replicated linkage results, and high-throughput association studies have yielded promising results. In this chapter, we integrate pieces of the genetics of MS; technical issues such as linkage disequilibrium (LD) mapping and the parent-of-origin effect are also discussed.