Lesch-Nyhan syndrome (LNS) is a rare, inherited disorder caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT). LNS is an X-linked recessive disease: the gene is carried by the mother and passed on to her son. LNS is present at birth in baby boys. Patients have severe mental and physical problems throughout life. The lack of HPRT causes a build-up of uric acid in all body fluids, and leads to symptoms such as severe gout, poor muscle control, and moderate mental retardation, which appear in the first year of life. A striking feature of LNS is self-mutilating behaviors, characterized by lip and finger biting, that begin in the second year of life. Abnormally high uric acid levels can cause sodium urate crystals to form in the joints, kidneys, central nervous system and other tissues of the body, leading to gout-like swelling in the joints and severe kidney problems. Neurological symptoms include facial grimacing, involuntary writhing, and repetitive movements of the arms and legs similar to those seen in Huntington's disease. The direct cause of the neurological abnormalities remains unknown. Because a lack of HPRT causes the body to poorly utilize vitamin B12, some boys may develop a rare disorder called megaloblastic anemia.

The symptoms caused by the buildup of uric acid (arthritis and renal symptoms) respond well to treatment with drugs such as allopurinol that reduce the levels of uric acid in the blood. The mental deficits and self-mutilating behavior do not respond to treatment. There is no cure, but many patients live to adulthood. LNS is rare, affecting about one in 380,000 live births. It was first described in 1964 by Dr. Michael Lesch and Dr. William Nyhan.

Features

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LNS is characterized by three major hallmarks: neurologic dysfunction, cognitive and behavioral disturbances, as well as uric acid overproduction (hyperuricemia). Some may also be afflicted with anemia (macrocytic). Virtually all patients are male, and male victims suffer delayed growth and puberty, and most develop shrunken testicles or testicular atrophy. Female carriers are at an increased risk for gouty arthritis, but are usually otherwise unaffected.

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Which of the following would rule out hyperuricemia in a patient? a. Lesch-Nyhan syndrome b. Gout c. Xanthine... http://t.co/jSHmwegS
prsdsrinivas (Prasad) Wed, 25 Jan 2012 05:25:50 -0000
Which of the following would rule out hyperuricemia in a patient? a. Lesch-Nyhan syndrome b. Gout c. Xanthine... http://t.co/jSHmwegS
HPRT deficiency, uric acid nephrolithiasis, compulsive self mutilation, choreoathetosis, mental retardation #Usmle ➡ Lesch Nyhan Syndrome
prep4USMLE (The USMLE geek) Mon, 23 Jan 2012 12:10:08 -0000
HPRT deficiency, uric acid nephrolithiasis, compulsive self mutilation, choreoathetosis, mental retardation #Usmle ➡ Lesch Nyhan Syndrome
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