Amerindian and genetically related populations in North America currently are affected by a pandemic of obesity, diabetes, and gallbladder disease. This has arisen in just the past 40–50 years; the conditions were previously rare in Amerindian populations. The rapid development of the pandemic thus implicates changes in lifestyle, very likely involving dietary patterns such as excess calories or newly adopted foodstuffs, which have occurred on a continental scale. ‘Urbanisation’, even in small settlements, seems to be associated with dramatically increased risk. The evidence also suggests that the conditions have a genetic basis; that is, there is an interaction between genetic susceptibility and the environmental risk factors. In 1984 Weiss, Ferrell, and Hanis synthesised a variety of indirect pieces of evidence to hypothesise that these conditions constitute a single genetic entity, or ‘syndrome’, that is, are biologically interconnected conditions sharing genetic risk factors. Subsequent research reports have been consistent with that idea. In this paper we review some of that evidence, and present new supportive results from studies in Mexican Mayan and Mvskoke Creek Amerindians. However, no gene or genes that are responsible and would prove the syndrome hypothesis have yet been identified.

Introduction

After World War II, numerous reports began to appear documenting a rapidly increasing prevalence of non-insulin-dependent diabetes mellitus (NIDDM) in many groups of Amerindians. Tribal groups from essentially every part of North America were affected, and there were suggestions that the same problems existed in Central and South America.