Seven GMs, including ABCC1 [38, 55], ADRB2 [47, 68, 69], EDNRA [29, 34], hemochromatosis (HFE) [43, 44], HLA [17, 83], interleukin 8 (IL-8) [65, 66], TCF7L2 [15, 16], and SLC11A1 [42, 70], had two studies conducted. This evidence concerns the gene TCF7L2 and hemochromatosis.