Alkaptonuria is considered by genetics as an error that arises within the metabolism process, an unusual genetic alteration, in which an individual’s urine adopts a dark brown pigmentation when exposed to air. That is why this unusual condition is within the group of rare diseases, known as “natural errors of metabolism”.

The first case of alkaptonuria in history was discovered in 1902 by Dr. Archibald Garrod, who in his research was able to find a gene that modifies the metabolic pathway. This disease was capable of generating arthritis in people that was accompanied by a flow of urine of a characteristic color (ocher yellow), in addition to this, alkaptonuria makes people’s bones and cartilage darker over time.

Alkaptonuria is considered the first disease to be assigned to a recessive inherited failure. The causes of the appearance of this condition are due to the lack of an enzyme in the liver: the so-called “homogenism oxidase”. The lack of this enzyme prevents the conversion of homogentisic acid, as a result of the metabolism of tyrosine and phenylalanine in acid. maleylacetoacetate. The dark pigmentation of urine is due to the fact that once it comes into contact with the air, the homogentisic acid that gathers in it tends to suddenly oxidize.

This disease usually does not usually show symptoms, except for the fact that the color of the urine is almost black; however, in some infants, they can occur, especially if they have family history of alkaptonuria. One of the consequences that arise as a result of this disease is the fact that the person after a certain age (between 40 and 60 years) can begin to manifest arthritic pain.

In order to make a diagnosis, urine tests are required. As for the treatment, it has not yet been possible to develop, which means that this condition cannot be treated. Although there are numerous specialists who consider that the intake of vitamin C, if taken in large quantities, can reduce the storage of brown coloration in the cartilage, which in turn would allow the reduction of the growth of arthritis.