Alkaptonuria - Overview
AKU; Alcaptonuria; Homogentisic acid oxidase deficiency; Alcaptonuric ochronosis
Definition of Alkaptonuria:
Alkaptonuria is a rare condition in which a person's urine turns a dark brownish-black color when exposed to air.
See also: Inborn error of metabolism
Causes, incidence, and risk factors:
A defect in the HGD gene causes alkaptonuria.
The gene defect makes the body unable to properly break down certain amino acids (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.
- Reviewed last on: 5/15/2011
- Chad Haldeman-Englert, MD, Wake Forest School of Medicine, Department of Pediatrics, Section on Medical Genetics, Winston-Salem, NC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
Chakrapani A, Holme E. Disorders of tyrosine metabolism. In: Fernandes J, Saudubray J-m, van den Berghe G, Walter JH, eds. Inborn Metabolic Diseases: Diagnosis and Treatment. 4th ed. New York, NY: Springer;2006:chap 18.
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