Medical Genetics: Revenge of the thrift

Abstract

Diet-induced obesity and Type II diabetes mellitus are escalating afflictions of Westernised society, and the factors controlling susceptibility, whether life style dependent or genetic, are the subject of intense scrutiny. In a recent issue of Heredity, Hillel et al (2005) have addressed the genetics underlying why some rodents are more prone than others to diabetes caused by a high-energy diet. The fat sand rat, Psammomys obesus, is an animal model illustrating the 'thrifty gene' hypothesis: the idea that certain gene variants provide an evolutionary advantage by allowing more efficient storage of scarce food energy, in preparation for times of famine. P. obesus is a desert-dwelling relative of the domestic gerbil. When its usual sparse diet of saltbush (Atriplex halimus) is replaced with higher energy foodstuffs, some individuals are found to be more prone to symptoms of Type II diabetes and excessive weight gain.