Human diabetes and obesity: tracking down the genes.

Diabetes mellitus and obesity are heterogeneous disorders that affect up to 5-8% of the population of Western Europe. The importance of genetic factors in these disorders is well established; however, the genes involved and the defects leading to the manifestation of disease are largely unknown. Family studies are a powerful tool with which to localize chromosomal regions linked to a genetic disorder. A genome-wide search for the genes associated with susceptibility to diabetes mellitus and obesity, combined with a more-specific, candidate-gene approach, should enable the identification of the loci involved in these diseases. Once regions linked to disease are identified, positional-cloning techniques can be used to track down the gene(s) responsible.