Homogentisic Acid Oxidase Deficiency
A deficiency of the hepatic enzyme homogentisate 1,2-dioxygenase (HGO) forces the accumulation of homogentisic acid, which is rapidly cleared in the kidney and excreted. Upon contact with air, homogentisic acid is oxidized to form a pigmentlike polymeric material responsible for the black color of standing urine.
- Dark spots in the sclera (white) of your eyes.
- Thickened and darkened cartilage in your ears.
- Blue speckled discoloration of your skin, particularly around sweat glands.
- Dark-colored sweat or sweat stains.
- Black earwax.
- Kidney stones and prostate stones.
It is caused by a mutation on your homogentisate 1,2-dioxygenase (hgd) gene. It's an autosomally recessive condition. This means that both of your parents must have the gene in order to pass the condition on to you. Alkaptonuria is a rare disease.