DDC has so far been implicated in aromatic L-amino acid decarboxylase deficiency disorder, while CLDN16 has been implicated in hypomagnesemia, hypercalciuria, and nephrocalcinosis, whereas NXT2 is involved in mRNA and protein transport, however, none of the three genes have been previously linked with HD. The gene discussed is CLDN16; the disease is nephrocalcinosis.