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 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. This condition is rare, affecting 1 in , to 1 million people worldwide.

Author:Kataur Grom
Language:English (Spanish)
Published (Last):6 May 2015
PDF File Size:10.91 Mb
ePub File Size:10.6 Mb
Price:Free* [*Free Regsitration Required]

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Making a diagnosis for a genetic or rare disease can often be challenging.

The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional. If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease.

You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists. Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved. Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services.

Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Inclusion on this list is not an endorsement by GARD. These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand.

You may want to review these resources with a medical professional. Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. National Institutes of Health. COVID is an emerging, rapidly evolving situation. Menu Search Home Diseases Alkaptonuria. You can help advance rare disease research!

Title Other Names:. Summary Summary. Symptoms Symptoms. The urine of individuals with AKU turns black when exposed to air. Children do not have symptoms of AKU other than the urine turning black when left to stand for a few minutes. 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 and commonly affects the cartilage of the ear, ligaments, tendons, blood vessels, kidneys, lungs and prostate. Dark spots on the white of the eye and cornea may also occur. 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, changes of the sound of the voice and prostate stones.

Showing of 39 View All. Abnormality of sight. Vision issue. High urine amino acid levels. Increased levels of animo acids in urine.

Joint pain. Whites of eyes are a bluish-gray color. Abnormal hearing. Joint dislocations. Recurrent joint dislocations. Stiff joint. Stiff joints. Degenerative joint disease. Nasal abnormality. Kidney stones. Inflammation of the prostate.

Rupture of tendons. Ruptured tendon. Narrowing and hardening of arteries. Heart attack. Low solidness and mass of the bones. Laboratory abnormality. Metabolism abnormality. Urinary tract abnormalities. Urinary tract abnormality. Urinary tract anomalies. Bulge in wall of large artery that carries blood away from heart. Joint inflammation. Disease of the joints.

Abnormal growth. Growth issue. Hunched back. Round back. Spinal fusion. Do you have more information about symptoms of this disease? We want to hear from you.

Do you have updated information on this disease? Diagnosis Diagnosis. Testing Resources. Treatment Treatment. 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.

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. Find a Specialist Find a Specialist. Healthcare Resources To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself.

Related Diseases Related Diseases. Conditions with similar signs and symptoms from Orphanet. Differential diagnosis includes acute intermittent porphyria, rheumatoid arthritis, ankylosing spondylitis and osteoarthritis. Visit the Orphanet disease page for more information. Research Research. Clinical Research Resources ClinicalTrials.



Alkaptonuria is a rare inherited disorder. This enzyme is used to break down a toxic substance called homogentisic acid. The buildup of homogentisic acid causes your bones and cartilage to become discolored and brittle. This typically leads to osteoarthritis, especially in your spine and large joints. There are few other symptoms during childhood.


Genetics of Alkaptonuria

Alkaptonuria and Ochronosis pp Cite as. Alkaptonuria AKU is a rare inherited disease caused by defects of the enzyme homogentisic acid dioxygenase, resulting in the accumulation of homogentisic acid in the body and its excretion in the urine. Its polymer, a yellow-black ochronotic pigment, deposits in cartilage and connective tissue, especially in the skin, visceral organs, eyes and ears causing their pigmentation ochronosis. From the clinical point of view, the most serious pigmentation is in joints, causing ochronotic arthropathy which usually results in severe disability. It is a degenerative process that primarily affects the spine causing calcification of intervertebral discs as well as large joints Rovensky and Urbanek Skip to main content.


Alkaptonuria is a rare inherited genetic disorder in which the body cannot process the amino acids phenylalanine and tyrosine , which occur in protein. Homogentisic acid and its oxidized form alkapton are excreted in the urine, giving it an unusually dark color. The accumulating homogentisic acid causes damage to cartilage ochronosis , leading to osteoarthritis and heart valves , as well as precipitating as kidney stones and stones in other organs. Symptoms usually develop in people over 30 years old, although the dark discoloration of the urine is present from birth. Apart from treatment of the complications such as pain relief and joint replacement for the cartilage damage , the drug nitisinone has been found to suppress homogentisic acid production, and research is ongoing as to whether it can improve symptoms. Alkaptonuria is a rare disease ; it occurs in one in , people, but is more common in Slovakia and the Dominican Republic.


Alternative titles; symbols. Alkaptonuria is an autosomal recessive metabolic disorder characterized by accumulation of homogentisic acid, leading to darkened urine, pigmentation of connective tissue ochronosis , joint and spine arthritis, and destruction of the cardiac valves summary by Vilboux et al. Alkaptonuria enjoys the historic distinction of being one of the first conditions in which mendelian recessive inheritance was proposed by Garrod, , on the suggestion of Bateson and of being 1 of the 4 conditions in the charter group of inborn errors of metabolism. The manifestations are urine that turns dark on standing and alkalinization, black ochronotic pigmentation of cartilage and collagenous tissues, and arthritis, especially characteristic in the spine. Cunningham et al. Carrier and Harris reported the case of a year-old man who underwent bilateral hip and knee total joint arthroplasties for the treatment of ochronotic arthropathy.

Related Articles