|
HealthTales.com |
|
| Index of Diseases and Conditions: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z |
Lesch-Nyhan syndrome is a condition characterized by the overproduction of uric acid, a nitrogen-containing compound found in blood and urine. The overproduction of uric acid can cause gouty arthritis (arthritis caused by uric acid in the joints), kidney stones, and bladder stones. Problems with the nervous system and behavioral disturbances are also characteristic of this disorder. Abnormal involuntary muscle movements such as flexing, jerking, flinging, and flailing are often displayed by people affected with this disorder. Self-injury, including biting and head banging, is the most common and distinctive behavioral problem in Lesch-Nyhan patients.
The prevalence of Lesch-Nyhan syndrome is approximately 1 in 380,000 individuals. This condition occurs with a similar frequency in all populations.
Mutations in the HPRT1 gene cause Lesch-Nyhan syndrome.
Mutations in the HPRT1 gene cause a severe deficiency of the enzyme hypoxanthine phosphoribosyltransferase 1. This enzyme is responsible for recycling purines, a type of building block for DNA and its chemical cousin RNA. When this enzyme is lacking, the breakdown of purines results in abnormal levels of uric acid in the body. It is unclear how a shortage of this enzyme causes the neurological and behavioral problems characteristic of Lesch-Nyhan syndrome.
This condition is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome (one of the two sex chromosomes). In males, who have only one X chromosome, one altered copy of the gene is sufficient to cause the condition. In females, who have two X chromosomes, a mutation must usually be present in both copies of the gene to cause the disorder. Males are affected by X-linked recessive disorders much more frequently than females. A striking characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
'''Lesch-Nyhan syndrome''', or '''LNS''', is a serious genetic disorder that affects mostly males. Patients have severe mental and physical problems throughout life, including severe gouty arthritis, kidney stones, mental retardation, and self-harm behavior, including chewing on their lips and fingers. LNS is due to mutations in the ''HPRT1'' gene, so named because it codes for the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT or HGPRT, EC number 2.4.2.8). This enzyme is involved in the biochemical pathways the body uses to produce purines, one of the components of DNA and RNA. Defects of this enzyme lead to increased production of uric acid. The buildup of uric acid is directly responsible for the arthritis and renal symptoms. These respond well to treatment with drugs such as allopurinol which reduce the levels of uric acid in the blood. The direct cause of the bizarre neurological abnormalities remains unknown. The mental deficits and self-mutilating behavior do not respond to treatment. There is no cure, but many patients live to adulthood. Since the ''HPRT'' gene is located on the XY sex-determination system, LNS is an X-linked inherited disease. LNS is rare, affecting about one in 380,000 live births. It was first described in 1964 in science by Dr. Michael Lesch and Dr. William Nyhan.
NINDS: Lesch-Nyhan Syndrome - Information sheet compiled by the National Institute of Neurological Disorders and Stroke.