TCF7L2 and gestational diabetes: rs7903146 of TCF7L2, which is an important component in Wnt signaling pathway involved in development of the pancreas and islets, was associated with GDM (C allele: OR = 1.51, 95% CI = 1.39–1.65, P<10−5, Supplementary figure 8; dominant model: OR = 1.69, 95% CI = 1.51–1.89, P<10−5).