GSTM1 and hemochromatosis type 1: These results are also consistent with the initial postulate that the increased mean MCV in adults with hemochromatosis is caused in part by the uptake of increased quantities of transferrin‐bound iron by immature erythroid cells and consequent increased Hb synthesis [10] and a subsequent postulate that HFE protein influences the availability of iron to erythroid cells [19].