Alkaptonuria is a rare inherited metabolic disorder that causes the body to produce an excessive amount of homogentisic acid (HGA). The excess HGA is then excreted in the urine, where it can react with air to produce a dark pigment called ochronosis. When the urine is left standing for a period of time, this pigment can accumulate and cause the urine to become dark in color.
What Causes Alkaptonuria?
Alkaptonuria is caused by mutations in the HGD gene, which is responsible for producing the enzyme homogentisic acid oxidase. This enzyme is responsible for breaking down HGA, so when the gene is mutated, the body is unable to properly reduce the levels of HGA in the body.
What Are The Symptoms of Alkaptonuria?
The most common symptom of alkaptonuria is darkening of the urine upon standing. Other symptoms include joint pain and stiffness, as well as darkening of the skin, eyes, and other tissues.
How Is Alkaptonuria Diagnosed?
Alkaptonuria is typically diagnosed through a combination of physical examination, family history, and laboratory tests. The most commonly used test is the urine ochronosis test, which detects the presence of ochronosis in the urine.
How Is Alkaptonuria Treated?
The treatment of alkaptonuria depends on the severity of the condition and the individual's symptoms. In general, treatment focuses on reducing the amount of HGA in the body, as well as managing the symptoms. This may include lifestyle changes, dietary modifications, and medications. In more severe cases, surgery may be necessary.