July 13, 2011
Why I chose this topic
I learned of this genetic disorder when I read about it in the Genetics notes. I found it fascinating that a disease could lead to self-mutilation. I wanted to find out more about the cause of this and other adverse effects.
What is Lesch-Nyhan syndrome?
Lesch Nyhan is a recessive X-linked recessive disorder meaning that is passed from mother to son via the X-chromosome. The disease is characterized by mental retardation, spastic cerebral palsy, renal abnormalities, self-injurious behaviors, and other abnormal neurologic symptoms. The condition is caused by a mutation in the HPRT gene, which encodes for the peptide hypoxanthine guanine phosphoribosyltransferase. This enzyme regulates the production of guanosine monophosphate and inosine monophosphate. It also serves in the recycling of purine nucleotides in the purine salvage pathway. Mutation in the HPRT gene are manifested at varying degrees of expressivity. For example, in men with 20% HPRT deficiency, hyperuricemia is a common result. This leads to high levels of uric acid in the blood, which causes gouty arthritis and/or the formation of uric acid stone in the urinary tract. Collectively, these symptoms categorize Kelly-Seegmiller syndrome. Female carriers of the disease are at increased risk for gouty arthritis. LNS can also cause deleyed growth and testicular atrophy.
Infants born with the condition usually never crawl, with few ever learning to talk. Due the neuromuscular symptoms of the disorder, it might be confused with cerebral palsy before other examinations can determine the actual condition. The self-mutilation behavior aforementioned, usually emerge at around age 3, with biting of the lips and tongue. As the disease progresses , sufferers many engage in finger biting and head banging. These behavior are present in 85% of males with LNS. Spitting, involuntary swearing, and overall aggression are commonly...
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