Ochronosis, often called alkaptonuric ochronosis, is an autosomal recessive metabolic disorder that causes an excess of homogentisic acid, resulting in adverse pigmentation, calcification, and inflammation of cartilagenous and related tissue throughout the body. The disorder is a result of incomplete metabolism of homogentisic acid, tyrosine and phenylalanine


Urine in an infant's diaper may darken and can turn almost black after several hours. However, many persons with this condition may not know they have it until mid-adulthood, around age 40, when joint and other problems occur. Symptoms may include: * Progressive arthritis, especially of the spine * Darkening of the ear * Dark spots on the white of the eye (sclera) and cornea


A defect in the HGD gene causes alkaptonuria. The gene defect makes the body unable to properly break down certain proteins (tyrosine and phenylalanine). As a result, a substance called homogentisic acid builds up in the skin and other body tissues. The acid leaves the body through the urine. The urine turns brownish-black when it mixes with air. Alkaptonuria is inherited, which means it is passed down from parents to their children. To get this disease, each of your parents must pass you a copy of the faulty HGD gene.


There is no know prevention.


The outcome is expected to be good.


Some patients benefit from high-dose vitamin C. This has been shown to decrease the build up of brown pigment in the cartilage and may slow the development of arthritis.