HAMP and Tangier disease: In iron metabolism, in vitro experiments have shown that reducing PCSK7 expression using siRNA leads to a significant decrease in HAMP (encoding hepcidin) mRNA levels in liver cancer cells, confirming the impact of PCSK7 on the expression of the key iron metabolism regulator hepcidin, and suggesting that PCSK7 gene variations could be one of the important genetic factors leading to primary iron overload [24].