Alkaptonuria is an inherited condition that is caused by a deficiency of the enzyme homogentisic acid (HGA) dioxygenase.
The three main features of alkaptonuria include
- ochronosis (bluish-black pigmentation in connective tissue),
- urine that turns black when exposed to air, and
The discoloration of connective tissue usually begins after age 30. Other associated signs and symptoms can include
- heart problems,
- kidney stones,
- prostate stones, and
- discoloration of the earwax.
Cause of alkaptonuria
The condition results from an inherited mutation in the homogentisate 1,2-dioxygenase (HGD) gene. This condition is inherited in an autosomal recessive pattern, in which a mutation must be inherited from each parent to cause the condition.
Other alkaptonuria symptoms and signs
- Discoloration of the Earwax
- Heart Problems
- Kidney Stones
- Ochronosis (Bluish-Black Pigmentation in Connective Tissue)
- Prostate Stones
- Urine That Turns Black When Exposed to Air
Main Article on Alkaptonuria Symptoms and Signs
Pictures, Images, Illustrations & Quizzes
Family Health History: Genetics, DNA Testing and Your Health
WebMD explains why your doctor asks about your relatives' health conditions and how you can get the information if you don’t know.
Genetics: 11 Surprising Things Your Genes Say About You
Explore what role DNA plays in your health, love life, and more in this WebMD slideshow.
Parenting & Children's Health Resources
Health Solutions From Our Sponsors
Subscribe to MedicineNet's Children's Health & Parenting Newsletter