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Ency. home > Disease > A > Alkaptonuria

Alkaptonuria   

Overview | Symptoms | Treatment | Prevention

Alternative names:

Alcaptonuria; Homogentisic acid oxidase deficiency; Ochronosis

Definition:

Alkaptonuria is a rare inherited disorder of metabolism characterized by urine which turns black when exposed to air. Another characteristic is the development of arthritis in adulthood.

Causes and Risks

Alkaptonuria is an autosomal recessive inherited disorder. It is a disorder of tyrosine (an amino acid) metabolism resulting from a defect in the enzyme homogentisic acid oxidase.

Homogentisic acid is excreted in the urine and turns a brown color upon exposure to air. This is the result of a dark pigment with an ochre color (earthy red or yellow) which led to the name ochronosis. The bones and cartilage of the body can be brown colored.

Ency. home > Disease > A > Alkaptonuria

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