Missing Genetic Link in Understanding Obesity Uncovered

As the obesity epidemic grows globally, scientists and physicians are scrambling to understand its origins, both genetic and environmental. Obesity is a complex trait with high heritability, so the delineation of genetic contributions to it has been an area of intense focus. One of the strongest signals correlating with body mass index, a measureable surrogate for obesity (weight (kg)/height (m2) is a gene called FTO, though the function of this gene and how, when variant, it impacts on obesity has been obscure. Recently, as published in the August 27, 2015 edition of The New England Journal of Medicine, a team of scientists from Boston led by Melina Claussnitzer has uncovered a mechanistic relationship between FTO and fat cells (adipocytes). These type of cells come in three varieties, white, brown and beige. The former type is important for fat storage, while the latter two types are involved in thermogenesis, the burning of fat. The beige cells are interspersed between the white cells (see figure), while the brown cells occupy solitary locations (over clavicles, adjacent to spinal column). These complex studies indicate that the FTO variant associated with obesity impairs the formation of beige adipocytes, decreasing the shift from energy storage to expenditure, which would then increase overall fat mass and body weight. This important work provides a possible strategy to increase thermogenesis and thus combat the epidemic.