In addition to the relationship between the Gly40Ser mutation and T2D, an elevated frequency of GCGR mutations has been found in probands from multiple (affected sibling pair) families with T1D, also known as insulin-dependent diabetes; however, the lack of preferential transmission from heterozygous parents to affected siblings with T1D suggests population stratification (48). The gene discussed is GCGR; the disease is type 2 diabetes mellitus.