Lesch-Nyhan

• X-linked recessive (Xq26)
• deficiency of HGPRT (hypoxanthine guanine phosphoribosyltransferase) in brain, liver and RBC's
• affects males (although females cases have been reported)

Course

• at birth, usually appears normal
• subsequently: hypotonia and developmental delay
• then: extrapyramidal signs like spasticicy, dystonia, hyperreflexia
• 2nd year of life: marked choreoathetosis (tx with levodopa, tetrabenazine, benzo) and blepharospasm
• orange-brown powdery substance in urine: hyperuricemia/hyperuricosuria
• nephrolithiasis can occur in children under 6 y/o (can lead to renal failure, prevent w/ allopurinol); later tophi and gouty arthritis
• compulsion to self-mutilate

Diagnosis

• serum uric acid > 4-5 mg/dL in a child with dystonia and self-injurious behavior.
• tests for HGPRT enzyme deficiency can confirm a questionable dx

Genetic counselling and prenatal screening

• identify carriers, do amniocentesis

Specialists

• peds, neuro, psych, SW, therapists.

Note: **Lesch-Nyhan can mimic Cerebral palsy, so it is important to screen children with an initial diagnosis of CP for Lesch-Nyhan, especially if the prenatal and perinatal courses were normal.**