Lesch-Nyhan syndrome

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Lesch-Nyhan syndrome is a rare X-linked genetic disease caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT).

Epidemiology

Affects 1 per 380,000 individuals, which are nearly all male given the X-linked inheritance .

Clinical presentation

hyperuricemia-related symptoms such as gouty arthritis and uric acid nephrolithiasis
neurological symptoms which can include extrapyramidal signs such as choreoathetosis and dystonia as well as cognitive defects
classic self-mutilating behaviors

Pathology

X-linked inherited absence of the nucleotide salvage enzyme HPRT leads to pathologic accumulation of uric acid as hypoxanthine, which would otherwise be recycled into nucleotides, is degraded into uric acid by xanthine oxidase .

Radiographic features

Ultrasound

Ultrasound of the renal tract shows:

increase in medullary echogenicity, which may be diffuse or patchy
increase in collecting system echogenicity
multiple uric acid stones

CT/MRI

Brain CT or MRI shows decreased cerebral volume with a predilection for white matter .

History and etymology

Discovered in 1946 by Michael Lesch, an American medical student at Johns Hopkins University, and his mentor William Nyhan, a pediatrician and geneticist .