Sex differences of iron turnover, as exemplified by protection of HFE gene homozygous mutant females from clinical hemochromatosis [22], the higher serum iron concentration found in Hp2,2 men but not Hp2,2 women, and the higher vitamin C concentration found in women [23] may all be important factors influencing effects of haptoglobin genotype. Here, HP is linked to hemochromatosis.