Genetic variations in uncoupling proteins are thought to lead to differences in the efficiency of people's metabolism. We test for variations in the UCP2 and UCP3 genes. UCP2 is expressed in many types of cells, amongst them muscle cells, cells of the lymph system and the cells that produce insulin. Your FitnessGenes result tells you which version of UCP2 you have and how you can expect it to affect your metabolism.
Uncoupling by UCPs (uncoupling proteins) have become an important focus for scientists to find ways to fight the world’s obesity problems. Uncoupling is a natural mechanism in the mitochondria where calories are ‘wasted’. All UCP’s have an effect on metabolic rate, and although not all their functions have been elucidated fully, their specific functions are related to where the proteins are expressed. We test for the the UCP’s of which the different genetic variations have shown to result in significant differences: UCP2 and UCP3.
UCP2 is present in many types of cells, and is highly present in the lymphoid system, in cells of the immune system (macrophages) and skeletal muscle fibers. Importantly, it is also expressed highly in the cells that produce insulin (pancreatic islets), making UCP2 one of the regulators of insulin secretion. UCP3 is mainly expressed in skeletal muscles. UCP3 is involved in fatty acid metabolism and protecting cells from oxidative damage.
Another uncoupling protein is UCP1, which is only present in mitochondria of brown fat cells (brown adipocytes) is related to body fat content. These fat cells are thermogenic (in small animals, babies and potentially adult humans) as they help to maintain body temperature. UCP2 and UCP3 are involved in the regulation of free radical levels in cells rather than in physiological uncoupling and cold induced thermogenesis like UCP1, but they do play a role in metabolic rate and possibly basal thermogenesis. For endurance athletes, the UCP2 VV variant with its association with a low metabolic rate seems to be beneficial but for the UCP3 gene, the AA genotype with its association with a high metabolic rate is more beneficial. This may be due to the types of cells these proteins are found. In skeletal muscle the fast A allele might be beneficial for use of fatty acids and regulation of oxidative damage.
Source: 1000 Genome Project. Global averages for both sexes