Related to the congenital deficiency of homogentisic acid oxidase.
Autosomal recessive:A disorder of tyrosine metabolism that results in high levels of homogenistic acid that subsequently polymerizes to form of pigment.
Homogentisic acid oxidase is an enzyme used in the degradation of tyrosine.
Homogentisic acid dioxygenase converts homogentisic acid to maleylacetoacetic acid.
Results in the buildup of homogenization that polymerizes to black brown pigment.
The condition manifests in childhood with darkening of urine after oxidation by air and in adulthood with pigmentation of connective tissue and early onset of severe osteoarthropathy.
Dark pigment accumulates in connective tissues, including cartilage.
Patient presents in adulthood with arthritis.
May turn sweat and urine turn black upon standing.
Process may be diagnosed by allowing urine to stand and noting color change.
Diagnosis can be made by measuring urine homogentistic acid.
Treatment with nitisnone, an enzyme inhibitor that reduces homogenistic acid production.