Alkaptonuria

Overview

What is Alkaptonuria?

Alkaptonuria is a genetic disease that happens when a person's body does not have the enzyme homogentisic dioxygenase (HGD). This enzyme helps break down a toxic compound called homogentisic acid, or HGA. When a person cannot break down HGA, it accumulates in the body and leads to a variety of health complications, many of which are not present until adulthood.

There are three main symptoms of Alkaptonuria. The first is HGA in the urine. This causes the urine to turn dark when it is exposed to air. However, darkening may not occur until several hours later. Many people with Alkaptonuria never notice this type of abnormal color to their urine. This may be the only sign of Alkaptonuria in children.

The second symptom is called ochronosis. This is a term that means a person's connective tissue has a bluish-black color. This color is caused by a buildup of HGA in connective tissue. People can see this coloring in the white parts of their eyes, ear cartilage, and on the skin of their hands from underlying tendons. People with Alkaptonuria may also see this coloring in their ear wax and in their sweat.

The last symptom is arthritis. People with Alkaptonuria typically have arthritis in their spine and in their large joints from the buildup of HGA.

SOURCE: Emory University - Department of Human Genetics in collaboration with ThinkGenetic • https://www.thinkgenetic.com/diseases/alkaptonuria-8246/overview/2322 • DATE UPDATED: 2016-06-06

References

Introne WJ, Perry MB, Troendle J, Tsilou E, Kayser MA, Suwannarat P, O'Brien KE, Bryant J, Sachdev V, Reynolds JC, Moylan E, Bernardini I, Gahl WA. A 3-year randomized therapeutic trial of nitisinone in alkaptonuria. Mol Genet Metab. 2011;103:307?14.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3148330/

Introne WJ, Gahl WA. Alkaptonuria. 2003 May 9 [Updated 2016 May 12]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016. Available from: http://www.ncbi.nlm.nih.gov/books/NBK1454/

Contact a ThinkGenetic Counselor

Do you have additional questions that haven't been answered? Ask a ThinkGenetic Counselor — a real expert in the field of genetics. Just fill out this form to send an email. We will be in touch within 48 hours.

Please sign me up for your mailing list.

This content comes from a hidden element on this page.

The inline option preserves bound JavaScript events and changes, and it puts the content back where it came from when it is closed.

Remember Me

Welcome to the ThinkGenetic beta. More content is added weekly so come back and check often. Please provide your feedback by filling out a contact us form.