Lesch-Nyhan
| Lesch–Nyhan syndrome | |
|---|---|
| Classification and external resources | |
| Specialty | endocrinology |
| ICD-10 | E79.1 |
| ICD-9-CM | 277.2 |
| OMIM | 308000 300322 |
| DiseasesDB | 7415 |
| MedlinePlus | 001655 |
| eMedicine | neuro/630 |
| Patient UK | Lesch–Nyhan syndrome |
| MeSH | D007926 |
| GeneReviews | |
Lesch–Nyhan syndrome (LNS), also known as Nyhan syndrome and juvenile gout, 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 William Nyhan, who published their findings in 1964.
The HGPRT deficiency causes a build-up of uric acid in all body fluids. The combination of increased synthesis and decreased utilization of purines leads to high levels of uric acid production. This results in both hyperuricemia and hyperuricosuria, associated with severe gout and kidney problems. Neurological signs include poor muscle control and moderate intellectual disability. 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's disease. The etiology 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 family history. LNS is present at birth in baby boys. Most, but not all, persons with this deficiency have severe mental and physical problems throughout life. There are a few rare cases in the world of affected females.
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