Last reviewed: April 26, 2010.
Lesch-Nyhan syndrome is an inheritable disorder that affects how the body builds and breaks down purines. Purines are a normal part of human tissue and help make up the body's genetic blueprint. They are also found in many different foods.
Causes, incidence, and risk factors
Lesch-Nyhan syndrome is inherited as an X-linked trait. It mostlyoccurs in boys. Persons with this syndrome are missing or are severely lacking an enzyme called hypoxanthine guanine phosphoribosyltransferase 1 (HGP). The body needs this enzyme to recycle purines. Without it, abnormally high levels of uric acid build up in the body.
The condition affects about 1 in 380,000 people.
The excess uric acid levels cause children to develop gout-likeswelling in some of their joints. In some cases, kidney and bladder stones develop because of the high uric acid levels.
Males with Lesch-Nyhan have delayed motor development followed by bizarre, sinuous movements and increased deep tendon reflexes. A striking feature of Lesch-Nyhan syndrome is self-destructive behavior characterized by chewing off fingertips and lips, if not restrained. It is unknownhow the enzyme deficiency causes these problems.
Signs and tests
There may be a family history of this condition.
The doctor will perform a physical exam. The exam may show:
* Overexaggerated reflexes
Blood and urine tests may reveal high uric acid levels. A skin biopsy may show decreased levels of the HGP enzyme.
No specific treatment exists for Lesch-Nyhansyndrome. The gout medication, allopurinol, successfully decreases uric acid levels, but does not improve the neurological outcome.
Some symptoms may be relieved with the drugs carbidopa/levodopa, diazepam, phenobarbital, or haloperidol.
The outcome is likely to be poor. Persons with this syndrome usually require assistance walking and sitting and generally need awheelchair to get around.
Severe, progressive disability is likely.
Calling your health care provider
Call your health care provider if signs of this illness appear in your child or if there is a history of Lesch-Nyhan syndrome in your family.
Genetic counseling for prospective parents with a family history of Lesch-Nyhan syndrome is recommended. Testing can be done to seeif a woman is a carrier of this syndrome.
Lesch–Nyhan syndrome (LNS), also known as Nyhan's syndrome, Kelley-Seegmiller syndrome and Juvenile gout:546, is a rare inherited disorder caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT), produced by mutations in the HPRT gene located on (the) X chromosome. LNS affects about one in 380,000 live births.The disorder was first recognized and clinically characterized by medical student Michael Lesch and his mentor, pediatrician Bill Nyhan, who published their findings in 1964.
The HGPRT deficiency causes a build-up of uric acid in all body fluids. This results in both hyperuricemia and hyperuricosuria, associated with severe gout and kidney problems. Neurological signs include poor muscle controland moderate mental retardation. These complications usually appear in the first year of life. Beginning in the second year of life, a particularly striking feature of LNS is self-mutilating behaviors, characterized by lip and finger biting. Neurological symptoms include facial grimacing, involuntary writhing, and repetitive movements of the arms and legs similar to those seen in Huntington'sdisease. The direct cause of the neurological abnormalities remains unknown. Because a lack of HGPRT causes the body to poorly utilize vitamin B12, some boys may develop megaloblastic anemia.
LNS is an X-linked recessive disease: the gene mutation is usually carried by the mother and passed on to her son, although one-third of all cases arise de novo (from new mutations) and do not have a...