Multifactorial obesity and disposing genes. Abstract.
Since the 1950’s obesity has become more and more common in the western world. The highest incidence is in the United States where 64 % of the population suffers from overweight and 30 % from obesity. Obesity increases in all parts of the world, and is about to reach pandemic proportions. Obesity is caused by a complex interplay of genetic and environmental factors. Obesity leads to severe comorbidity, and it is of great importance to learn more about the genes that predispose to obesity. Since the 1990’s geneticists have tried to identify gene variants leading to an increased risk of developing obesity through candidate gene studies and genome-wide association studies. Several genes and quantitative trait loci have been found to have a modest effect on body weight, but no single gene or chromosomal region has so far unequivocally been linked to obesity.
Through candidate gene studies variants of several genes, i.e. ADRB2, ADRB3, UCP2, UCP3 and PPARG, have been found to have some effect on body weight. Through genome-wide association studies, which is a new approach, FTO and a few other previously unknown genes have been identified as contributors to the phenotype of body weight and composition. A major problem has been the reproduction of positive results, typically one positive association study beeing followed by several negative ones. A great challenge is to elucidate the reasons for this, and to develop new study designs, also considering gene-gene and gene-environment interactions.
In this paper I will present an overview of today’s genetic research on multifactorial obesity.