It's quick and easy to access Live Science Plus, simply enter your email below. We'll send you a confirmation and sign you up for our daily newsletter, keeping you up to date with the latest science news.
Patients with alkaptonuria have dark-stained connective tissues and black urine because a genetic mutation causes an enzyme involved in protein metabolism to malfunction.
(Image credit: Antonio Hugo Photo via Getty Images)
Disease name: Alkaptonuria, also known as "black urine disease"
Affected populations: The exact prevalence of alkaptonuria worldwide is unknown. However, estimates suggest that the disease affects between 1 in 250,000 and 1 in 1 million people in the U.S. More than 1,000 cases of alkaptonuria have been reported in the medical literature. Individuals from any group can potentially develop the disease, regardless of their sex, race or other factors. However, alkaptonuria is a recessive genetic disorder, meaning people will only develop it if they inherit two faulty copies of a specific gene — one from each of their parents.
Causes: People with alkaptonuria are unable to fully break down all the building blocks of proteins that they consume or that their body makes. This is because a mutation in a gene called homogentisate 1,2-diooxygenase (HGD) causes an enzyme that normally does the job to malfunction. Consequently, a chemical called homogentisic acid accumulates in different tissues in the body, especially in connective tissues, such as cartilage.
Symptoms: One of the earliest signs that someone has alkaptonuria is dark stains in their diapers as babies, because the homogentisic acid in their urine turns black upon exposure to air.
Besides dark urine, people with alkaptonuria often have no other noticeable symptoms of the disease until they are in their late 20s or early 30s.
Treatments: There is currently no cure for alkaptonuria, but scientists are studying the potential use of a drug called nitisinone to slow the progression of the disease. Affected individuals can also take steps to manage their symptoms, including taking painkillers and exercising regularly to help strengthen their joints. Adopting a low-protein diet can also help some patients.
Around half of patients with alkaptonuria will require hip, knee or shoulder joint replacement, usually by the age of 50 or 60.
Disclaimer
This article is for informational purposes only and is not meant to offer medical advice.
Sign up for the Live Science daily newsletter now
Get the world’s most fascinating discoveries delivered straight to your inbox.
Emily is a health news writer based in London, United Kingdom. She holds a bachelor's degree in biology from Durham University and a master's degree in clinical and therapeutic neuroscience from Oxford University. She has worked in science communication, medical writing and as a local news reporter while undertaking NCTJ journalism training with News Associates. In 2018, she was named one of MHP Communications' 30 journalists to watch under 30.
You must confirm your public display name before commenting
Please logout and then login again, you will then be prompted to enter your display name.
Live Science Plus
