TCF7L2 and type 2 diabetes mellitus: Genome-wide linkage scans have discovered chromosomic regions containing type 2 diabetes (T2D) susceptibility genes in chromosome 10q, which were later ascribed to intronic variations in the transcription factor 7-like 2 (TCF7L2) gene, which were strongly associated with a twofold increase in risk for T2D in an Icelandic population [1].