Genetics of Obesity: Etiologic Heterogeneity and Temporal Trends

Phenotypes devised to quantitate the degree of obesity have been the subject of many recent investigations, motivated by the increased risk of cardiovascular morbidity and mortality, largely through increased risk of diabetes, hypertriglyceridemia, changes in plasma lipoprotein profile and composition, and hypertension. The observation that the prevalence of obesity has been increasing in developed countries over the last half century is consistent with studies suggesting the importance of non-shared environmental influences. A model to assess temporal trends in familial correlations under multifactorial inheritance has been developed in the context of path analysis, using a simple tau model. Identification of the determinants of human obesity is a complex problem and poses numerous research challenges. It is clear that each of polygenic, shared environmental, unique environmental, and major gene factors all have been implicated in various studies, and the evidence for the presence and magnitude of each is not entirely consistent across all studies.