Kidneys: renal tubular acidosis (Type 2), a disorder of bicarbonate handling by the proximal tubules leads to nephrocalcinosis (calcium accumulation in the kidneys), a weakening of bones (due to calcium and phosphate loss), and occasionally aminoaciduria (loss of essential amino acids needed for protein synthesis). Heart: cardiomyopathy (weakness of the heart muscle) is a rare but recognized problem in Wilsons disease; it may lead to heart failure (fluid accumulation due to decreased pump function) and cardiac arrhythmias (episodes of irregular and/or abnormally fast or slow heart beat). Hormones: hypoparathyroidism (failure of the parathyroid glands leading to low calcium levels), infertility, and recurrent miscarriage. Genetics
The Wilsons disease gene (ATP7B) is on chromosome 13 (13q14.3) and is expressed primarily in the liver, kidney, and placenta. The gene codes for a P-type (cation transport enzyme) ATPase that transports copper into bile and incorporates it into ceruloplasmin. Mutations can be detected in 90% of cases. Most (60%) are homozygous for ATP7B mutations (two abnormal copies), and 30% have only one abnormal copy. Ten percent have no detectable mutation.Although 300 mutations of ATP7B have been described, in most populations the cases of Wilsons disease are due to a small number of mutations specific for that population. For instance, in Western populations the H1069Q mutation (replacement of a histidine by a glutamine at position 1069 in the protein) is present in 37–63% of cases, while in China this mutation is very uncommon and R778L (arginine to leucine at 778) is found more often.
Penicillamine is not without problems: about 20% experience a side effect or complication of penicillamine treatment, such as drug-induced lupus (causing joint pains and a skin rash) or myasthenia (a nerve condition leading to muscle weakness). In those who presented with neurological symptoms, almost half experience a paradoxical worsening in their symptoms. While this phenomenon is observed in other treatments for Wilsons, it is usually taken as an indication for discontinuing penicillamine and commencing second-line treatment. Those intolerant to penicillamine may instead be commenced on trientine hydrochloride, which also has chelating properties. Some recommend trientine as first-line treatment, but experience with penicillamine is more extensive. A further agent, under clinical investigation by Wilson Therapeutics, with known activity in Wilsons disease is tetrathiomolybdate. This is regarded as experimental, though some studies have shown a beneficial effect.Once all results have returned to normal, zinc (usually in the form of a zinc acetate prescription called Galzin) may be used instead of chelators to maintain stable copper levels in the body. Zinc stimulates metallothionein, a protein in gut cells that binds copper and prevents their absorption and transport to the liver. Zinc therapy is continued unless symptoms recur or if the urinary excretion of copper increases.In rare cases where none of the oral treatments are effective, especially in severe neurological disease, dimercaprol (British anti-Lewisite) is occasionally necessary.