Patients with Lesch-Nyhan syndrome often engage in self-harm, including biting their fingers. (Photo by Paulo Souza via Getty Images)
Disease name: Lesch-Nyhan syndrome
Affected populations: Lesch-Nyhan syndrome is an extremely rare genetic disorder that causes metabolic abnormalities and predominantly affects males. It is estimated that about 1 in 380,000 newborns in the United States have the condition.
Causes: Lesch-Nyhan syndrome is caused by mutations in the HPRT1 gene. This gene provides instructions for an enzyme that cells use to process important chemicals known as purines; these are found, for example, in DNA and molecules that interact with enzymes. Purines are also found in many foods, such as organ meats, poultry, and legumes.
In patients with Lesch-Nyhan syndrome, the HPRT1 enzyme does not function correctly due to mutations in the corresponding gene. As a result, cells cannot process purines as they normally do, leading to a buildup of a substance known as uric acid in the blood.
Excess uric acid also forms small stones or crystals in various parts of the body, including joints and kidneys.
Patients with Lesch-Nyhan syndrome also have lower levels of the brain chemical dopamine than people without the condition for unknown reasons. Dopamine plays an important role in controlling movement and processing emotions, among other functions.
The HPRT1 gene is located on the X chromosome, one of two sex chromosomes in humans; females typically have two X chromosomes (XX), while males have one X and one Y (XY).
Because women have two X chromosomes, if the HPRT1 gene on one chromosome mutates, the unmutated version on the other chromosome can effectively compensate. However, men only have one X chromosome, and if it contains a mutant HPRT1 gene, they will develop Lesch-Nyhan syndrome. This is why the condition almost exclusively affects men.
This microscopic image shows uric acid crystals building up in the joints of a person with gout.
Although the syndrome is usually inherited, it can occur in people with no family history of the condition due to random mutations in the HPRT1 gene that occur during pregnancy.
To date, more than 600 mutant versions of the HPRT1 gene associated with Lesch-Nyhan syndrome have been identified.
Symptoms: The main symptoms of Lesch-Nyhan syndrome are related to inflammatory arthritis, a set of conditions caused by the immune system,
Sourse: www.livescience.com
