TGFBR1 and hereditary nonpolyposis colon cancer: The observed frequencies of TGFBR1*6A genotypes in cases and controls were in accordance with Hardy–Weinberg laws of equilibrium (P=0.35 and 1.00 in familial non-HNPCC and HNPCC cases; P=0.86 in controls), providing no evidence of population stratification within the dataset.