Lesch-Nyhan disease (LND) is a rare, X-linked genetic disorder
that involves the nearly complete absence of an enzyme
(hypoxanthine-guanine phosphoribosyltransferase, or HPRT) that
is essential for purine salvage. In addition to hyperuricemia,
all patients with classic LND suffer from movement disorder
and compulsive self-injury, and most have mental retardation.
Patients with partial HPRT deficiency (variants) always have
hyperuricemia and often have neurologic abnormalities, but do
not self-injure and usually are described as having normal
intelligence. Here we compare 15 patients with LND to 9 variants
and 13 normal adolescents and adults. Testing revealed unambiguous
and qualitatively similar cognitive deficits in both patient
groups. The variants produced scores that were intermediate
between those of patients with LND and normal participants on
nearly every cognitive measure. We discuss these findings in
terms of what is known about the neuropathology of LND.
(JINS, 2001, 7, 805–812.)
