Journal of Genetic Disorders

Alkaptonuria may be a rare genetic disorder characterized by the buildup of alkapton within the body. Affected individuals lack enough functional levels of an enzyme required to breakdown alkapton . Affected individuals may have dark urine or urine that turns black when exposed to air. However, this alteration might not occur for several hours after urination and sometimes goes unnoticed. apart from dark urine that's present from infancy, affected individuals generally don't develop symptoms (asymptomatic) during infancy or childhood and sometimes remain unaware of their condition until adulthood. Affected individuals eventually develop ochronosis, which is that the bluish-black discoloration of connective and other tissue within the body. Affected individuals may develop discoloration of the skin overlying cartilage within the body like over a part of the external ear . In some cases, the whites of the eyes (sclera) can also become discolored. In adulthood, affected individuals also develop progressive arthritis of the spine and enormous joints. The HGD gene codes for the enzyme required for the breakdown of alkapton . Mutations within the HGD gene cause alkaptonuria.