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Diseases

Genetic and Rare Diseases Information Center (GARD)

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Your Question

My brother was diagnosed with ochronosis, and he has alkaptonuria. He was told that there are no treatments for this condition. Do you know of any treatments available?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is ochronosis?

Ochronosis is the bluish-black discoloration of certain tissues, such as the ear cartilage, the ocular (eye) tissue, and other body locations. It often occurs in individuals with alkaptonuria, a metabolic disorder; it can also occasionally occur from exposure to various substances. Alkaptonuria is caused by a mutation in the HGD gene, which results in the accumulation and deposition of homogentisic acid (HGA) in cartilage, causing the characteristic coloring of ochronosis. The affected tissue becomes weak and brittle with time, leading to chronic inflammation, degeneration, and osteoarthritis. Alkaptonuria is inherited in an autosomal recessive manner. When ochronosis is due to exposure to substances (called exogenous ochronosis), the condition is not inherited.[1]
Last updated: 2/10/2011

What is alkaptonuria?

Alkaptonuria is an inherited condition that causes urine to turn black when exposed to air. Ochronosis, a buildup of dark pigment in connective tissues such as cartilage and skin, is also characteristic of the disorder. This blue-black pigmentation usually appears after age 30. People with alkaptonuria typically develop arthritis, particularly in the spine and large joints, beginning in early adulthood. Other features of this condition can include heart problems, kidney stones, and prostate stones. Alkaptonuria is caused by mutations in the HGD gene. It is inherited in an autosomal recessive fashion.[2]
Last updated: 8/1/2011

How might alkaptonuria be treated?

There is no cure for alkaptonuria, but there is treatment for some individual signs and symptoms of the condition. Joint pain may be substantial in individuals with alkaptonuria, and close attention to pain control is usually necessary. Physical and occupational therapy can be important to promote muscle strength and flexibility. Knee, hip, and shoulder replacement surgeries may be options for managing significant arthritis. In general, however, the goal of joint replacement is pain relief rather than increased range of motion. Maintaining joint range of motion through moderate non-weight-bearing exercise such as swimming may have beneficial effects. Treatment of prostate stones and renal stones may include surgery.[3]

Several therapies for alkaptonuria have been investigated. Treatment of alkaptonuria with nitisinone (also called NTBC) has been proposed; nitisinone is currently approved for the treatment of tyrosinemia type I, which is also a metabolic disorder. Further investigations to determine the benefits of nitisinone in slowing the progression of joint disease are in progress.[3] To see a list of completed clinical trials or trials currently enrolling individuals with alkaptonuria, click here.

No therapy has proven to prevent or correct the pigmentary changes of ochronosis.[3]
Last updated: 8/1/2011

How can I find a genetics professional in my area?

Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.

The following online resources can help you find a genetics professional in your community:
Last updated: 10/18/2013

References