Also known as hepatolenticular degeneration, Wilson disease is an autosomal recessive disorder that occurs in 1 of 30,000 individuals. The abnormal gene, the ATP7B (adenosine triphosphate) gene, is located on chromosome 13. The defective protein, adenosine triphosphatase (ATPase), is involved in the transport and incorporation of copper into ceruloplasmin and the vesicular compartment near the canalicular membrane for further bile excretion.
Although
a neurologic disorder, it affects multiple organs, with the liver being the
most common and earliest affected. Approximately 40% of newly diagnosed cases
have hepatic involvement. Neurologic manifestations include dysarthria,
dystonia, rigidity, wing beating tremor, and choreoathetosis. Children
younger than 10 years rarely present with neurologic involvement. Progressive
dementia, antisocial behavior, impulsivity, and decreased intellectual
performance further complicate the disease and are important manifestations.
The Kayser-Fleischer ring, the classic ophthalmologic sign of the
disease, is a yellowbrown
discoloration of the Descemet membrane, best demonstrated by slitlamp examination. In
addition, sunflower cataracts may be noted. Careful bedside ophthalmologic
evaluation may reveal KayserFleischer
rings in suspected cases. Other features include hemolytic anemia, renal
failure with tubular dysfunction, nephrolithiasis, cardiomyopathy,
hypoparathyroidism, amenorrhea, and testicular atrophy.
Diagnosis
requires a strong index of suspicion and should be considered in all patients,
particularly those younger than 40 years, presenting with abnormal involuntary
movements, and those presenting with abnormal liver function. Although not
specific, 24hour
urinary copper excretion and serum copper and ceruloplasmin levels are useful
screening tests. The single best confirmatory test for the diagnosis is elevated
hepatic copper levels, but this requires a liver biopsy; this is performed only
in cases in which the diagnosis is unclear but the index of suspicious is high.
On neuroimaging, a brain MRI shows atrophy of cerebrum, brainstem, and less
commonly cerebellum. The face of the giant panda sign (globus pallidus
hypointensity) is a characteristic MRI finding on T2weighted imaging seen in 34% of cases.
The
copperchelating agent dpenicillaminehas been
considered the gold standard of therapy. In patients who cannot tolerate
penicillamine, trientine, another copperchelating
agent, has been used. In patients with cirrhosis or fulminant hepatic failure,
liver transplantation is the only option.
