Lesch-Nyhan Syndrome (LNS)
Lesch-Nyhan syndrome (LNS) is characterized by uric acid overproduction, behavioral problems, and neurologic disability. This genetic condition only affects males and the severe stage is characterized by renal failure, arthritis, dystonia, intellectual disability, involuntary writhing, facial grimacing, and repetitive and impulsive behaviors such as self-mutilation.
The symptoms often appear during the first year of life and self-harm such as finger biting and lip biting typically manifest during the second year of life. It is a rare disorder due to a mutation of the Hypoxanthine Phosphoribosyltransferase (HPRT) gene on the X-chromosome. This was first described by Michael Lesch, a Jewish American physician, and William Leo Nyhan, an American physician, in the mid-1960s.