Rare inborn error of purine metabolism that becomes
apparent between the ages of 3 and 6 months. Characterized by the presence
of orange crystal-like deposits (“orange sand”) in the diapers of infants
with the disorder. This is frequently the first symptom of Lesch-Nyhan
syndrome. Other clinical features include hematuria, urinary tract
infections, arthritis, choreoathetosis manifested by raising and lowering of
the shoulders, and facial grimacing. Hypotonia, hypertonia, hyperreflexia,
and spasticity have been reported. Megaloblastic anemia, self-mutilating
behavior, irritability, screaming, uncontrolled aggressiveness, and
compulsive actions complete the clinical presentation.