Alkaptonuria

Definitions & Key takeaways

Alkaptonuria is a rare inherited disorder in which a deficiency of an enzyme called homogentisate 1,2 dioxygenase - HGD, results in the accumulation of homogentisic acid in connective tissues. This build-up causes arthritis, increased risk for the formation of renal and gallbladder stones, and the risk of tendon and ligament ruptures. People with alkaptonuria can also present with vision and hearing problems, and have dark urine.