onchronosis

Ochronosis is a condition resulting from alkaptonuria, a rare inherited disorder of protein metabolism. In individuals with alkaptonuria, the body cannot properly metabolize the amino acids tyrosine and phenylalanine. This leads to a buildup of homogentisic acid, which oxidizes and turns urine black.1

While alkaptonuria has no symptoms until adulthood, the accumulated homogentisic acid deposits in connective tissues, causing ochronosis. These ochre pigments bind to collagen in cartilage and intervertebral disks, making them brittle and leading to degenerative joint disease. The term "ochronotic" describes something related to or marked by ochronosis. Alkaptonuria does not typically affect life expectancy.12