Review Question - QID 106253

The clinical case described above is suggestive of Lesch-Nyhan syndrome (LNS). LNS is inherited via an X-linked recessive mode of inheritance.

LNS is due to an absence in an enzyme in the purine salvage pathway called hypoxanthine-guanine phosphoribosyltransferase (HGPRT). The lack of HGPRT results in the inability to convert guanine and hypoxanthine to guanylic acid and inosinic acid, as a result leads to an increased uric acid production as purine bases cannot be recycled. The symptoms resulting from this deficiency are compulsive self-mutilation, especially of the oral/perioral areas, mental retardation, aggression, choreoathetosis, generalized dystonia, and hyperuricemia which may develop into gout.

Kale et al. report on a case of LNS in which a 6-year-old male presents with lip lacerations due to a self-mutilating behavior (See Illustration A). The child had been quiet during infancy, but at the age of 2 he became very aggressive and started biting his toes and fingers. When the bandages were removed from his hands and feet, the physician noted that there were no fingers left and he was also missing the toes on his right foot (See Illustration B & C).

Arhakis et al. report on treatments for self-mutilation caused by LNS. Medications to prevent the self-mutilation have produced questionable results, but procedures such as extraction of teeth to prevent biting and orthognathic surgery have been used with better success.

Illustration A, B, & C are images of self-mutilation from a 6-year old with LNS (See case report above for more information).

Incorrect Answers:
Answers 2-4: LNS does not have the following modes of inheritance: X-linked dominant, autosomal dominant or recessive, and is not passed on via defective maternally mitochondria.