alcaptonuria, alkaptonuria

Excretion of homogentisic acid (alkapton) in the urine due to congenital lack of the enzyme homogentisate 1,2-dioxygenase, which mediates an essential step in the catabolism of phenylalanine and tyrosine; urine turns dark if allowed to stand or is alkalinized (a result of formation of polymerization products of homogentisic acid); frequently occurs throughout relatively long periods or may recur and subside at irregular intervals; arthritis and ochronosis are late complications; autosomal recessive inheritance.


[alkapton + G. ouron, urine]