Homogentisate 1,2-dioxygenase (HGD) gene mutations are the molecular cause of alkaptonuria, a rare hereditary disorder of the phenylalanine catabolism. The highest expression of HGD is in the prostate, small intestine, colon, and liver. The HGD gene contains 14 exons. Conflicting reports have placed the gene at 3q2, 3q13.3-q21, 3q21-q24, 3q21-q23, or 3q25-q26. [provided by RefSeq
