To understand how the 62 iron homeostasis variants affect either IDA or iron overload, we tested for association with IDA (defined as ever simultaneously having hemoglobin < 120 g/L for women, <130 g/L for men, MCV < 80 fl, MCH < 27 pg and either ferritin < 10 mcg/L or TSAT < 16%; Ncases = 6476, Ncontrols = 362,706)5 and iron overload (defined as TSAT ever >50%4, Ncases = 4156, Ncontrols = 342,647) (Fig. 5, Supplementary Data 12), correcting for 2 × 62 = 124 performed tests. This evidence concerns the gene PMCH and Tangier disease.