Ochronosis (Alkaptonuria)

What is Ochronosis?

Alkaptonuria, is a metabolic disease where the body is missing an enzyme to break down homogentisic acid. If you have alkaptonuria, you may eventually develop ochronosis, where connective tissue in your body turns a blue-black color.

Adults with ochronosis typically go on to develop arthritis of the spine and large joints.

What are the Symptoms of Ochronosis?

Ochronosis is a genetic disorder, but patients usually live symptom free until they turn 30 years old. That’s when the cumulative build-up of homogentisic acid in cartilage and other connective tissue begins to turn color and become thick and irregular. Homogentisic acid is typically found in honey and some types of yeast. It’s also an intermediate product as the body makes some types of amino acids.

If you have ochronosis, you may also see the whites of your eyes, called the sclera, become discolored. Your connective tissue, including tendons and ligaments, begin to become weak and you may get more injuries. Lower back pain is common. Arthritis develops in the spine and can lead to curvature and loss of height as well as increased pain.

Joints can be impacted and fluid can build up in your knees and elbows. Mobility is impacted and sufferers have a harder time engaging in physical activity.

The heart can also be damaged as the valve tissue thickens and openings narrow. You may have an increased risk of heart disease or heart failure.

Some patients with alkaptonuria and ochronosis also have a higher chance of getting kidney stones. Men may develop prostate stones.

Ochronosis Causes

The major cause of ochronosis is a rare genetic disorder called Alkaptonuria. This is an autosomal recessive condition in which the HGD enzyme or homogentisate 1,2-dioxygenase becomes inactive. This results in the accumulation of homogentisic acid within the liver.

Another common cause of Ochronosis is the continued use of skin lightening products. Most skin lightening products contain an active ingredient called hydroquinone. Specifically, hydroquinone inhibits the enzyme homogentisic acid oxidase, resulting in the accumulation of this substance on the collagen fibers in areas where the lightening product has been applied. The reaction over time results in grayish brown or bluish black patches and bumps on the skin. This condition is called exogenous ochronosis. Even in small amounts, continued exposure to hydroquinone can result in the development of lesions causing ochronosis. The severity of ochronosis depends on how long your skin is exposed to hydroquinone containing products. In addition, medical conditions like melisma require the use of compounds that contain hydroquinone and hence are responsible for the development of ochronosis.

How is Ochronosis Treated?

There’s no way to cure alkaptonuria or ochronosis, but you can treat the associated pain and symptoms. Your doctor may prescribe pain medication depending on the severity of your conditions.

Physical therapy can help maintain mobility in the joints and keep patients more active for longer.

Surgery can help conditions associated with the spine. Sometimes fusions and disk surgeries can help reduce pain.

Some medical professionals are experimenting with high doses of Vitamin C to help prevent the accumulation of homogentisic acid, but there are no definitive medical studies to prove the effectiveness of this treatment.

Ochronosis Prevention

As a prevention mechanism, avoid long-term use of skin whitening products that have hydroquinone concentrations greater than 2%. Instead, go for natural skin lightening products. Another way of preventing ochronosis is by excessive exposure to direct sunlight to limit skin damage. While there are no specific methods of preventing Alkaptonuric Ochronosis because it is a genetic condition, undergoing a genetic test when expecting may help to better understand the risks during pregnancy. In cases where there is a history of ochronosis in the family, genetic counseling can be used to assess the risk before planning for a child.

Active research is currently underway on how to prevent inherited genetic conditions such as alkaptonuria. Routine screening at periodic intervals with physical examinations, tests and scans are also recommended as preventive measures for exogenous ochronosis.