ochronosis

aka: alkaptonuria

autosomal recessive
excessive homogentisic acid
- no homogentisic acid oxidase
- part of phenylalanine / tyrosine pathway
alkaptonuria: brown/black urine
ochronosis: brown/black pigmentation of skin, mucous membranes
pigment deposition in articular cartilage of joints
- ==> chronic arthritis (usually evident in 4th decade)
narrowed, calcified intervertebral disks
renal calculi
nephrocalcinosis

Charles E. Kahn, Jr., MD - 2 February 1995
Last updated: 1 October 2013