Oral zinc sulphate as primary therapeutic intervention in a child with Wilson disease

Zinc Monotherapy as an Alternative Treatment Option for Decompensated Liver Disease due to Wilson Disease?

Background

Wilson disease is a rare metabolic disorder involving copper metabolism, and patients may present with a variable degree of hepatic, neurologic, and psychiatric manifestations. In the case of hepatic presentation, treatment is usually initiated with potentially toxic copper chelators (D-penicillamine or Trenton). Although zinc is of low toxicity and low cost for treatment of Wilson disease, it has been limited to the adjunctive as a single maintenance drug or for asymptomatic patients. The use of zinc monotherapy in patients suffering from a severe liver disease was not well studied. In our case report, we describe a pediatric patient who presented with liver failure and the use of zinc monotherapy in patients with severe hepatic manifestations. Case presentation. A 15-year-old male patient from Ethiopia presented with generalized body swelling (edema and ascites) with yellowish discoloration of his eyes and easy fatigability. He had hyperbilirubinemia, coagulopathy, hypoalbuminemia, and deranged liver enzymes. He had a Keyser–Fleischer ring visible with the naked eye, which was confirmed by slit-lamp examination. He had very low serum ceruloplasmin (<8 mg/L) and high 24-hour urine copper (150 mcg/dl). In accordance with the scoring system proposed by the 8th International Meeting on Wilson Disease and Menkes Disease, a diagnosis of Wilson disease was made. Zinc monotherapy with low copper diet was initiated for decompensated liver disease due to Wilson disease because of the inaccessibility of chelators (D-penicillamine or Trientine). After months of treatment with zinc, the patient experienced normalization of hepatic synthetic function and resolution of hypoalbuminemia and coagulopathy. The patient had also clinically stabilized (ascites, lower extremity swelling, edema, and jaundice were improved. Currently, the patient is on follow-up almost for the last four years in the gastrointestinal clinic.

Conclusion

Our case shows that zinc has the potential for treatment in improving liver function. Though zinc has its own side effects, it is important and maybe an alternative treatment option in those with limited resources (not able to access chelators). This example hopefully will encourage future investigations and researches on zinc monotherapy for treating symptomatic decompensated hepatic Wilson disease.

Function and regulation of human copper-transporting ATPases

Copper-transporting ATPases (Cu-ATPases) ATP7A and ATP7B are evolutionarily conserved polytopic membrane proteins with essential roles in human physiology. The Cu-ATPases are expressed in most tissues, and their transport activity is crucial for central nervous system development, liver function, connective tissue formation, and many other physiological processes. The loss of ATP7A or ATP7B function is associated with severe metabolic disorders, Menkes disease, and Wilson disease. In cells, the Cu-ATPases maintain intracellular copper concentration by transporting copper from the cytosol across cellular membranes. They also contribute to protein biosynthesis by delivering copper into the lumen of the secretory pathway where metal ion is incorporated into copper-dependent enzymes. The biosynthetic and homeostatic functions of Cu-ATPases are performed in different cell compartments; targeting to these compartments and the functional activity of Cu-ATPase are both regulated by copper. In recent years, significant progress has been made in understanding the structure, function, and regulation of these essential transporters. These studies raised many new questions related to specific physiological roles of Cu-ATPases in various tissues and complex mechanisms that control the Cu-ATPase function. This review summarizes current data on the structural organization and functional properties of ATP7A and ATP7B as well as their localization and functions in various tissues, and discusses the current models of regulated trafficking of human Cu-ATPases.

Zinc acetate treatment in Wilson's disease

OBJECTIVE

To briefly review the pathophysiology and diagnosis of Wilson's disease, and to evaluate the pharmacology, pharmacokinetics, clinical utility, adverse effects, dosing regimens, and pharmacoeconomics of zinc acetate therapy in Wilson's disease.

DATA SOURCES

A MEDLINE search (December 1966-December 1996) of the English-language literature using the terms zinc and Wilson's disease was conducted to identify pertinent clinical trials, review articles, and case reports. Additional articles were selected from bibliographies of the reviewed literature.

STUDY SELECTION AND DATA EXTRACTION

Due to the rarity of the disease, all articles were considered for possible inclusion in this review. Single case reports are referenced, but were not selected for evaluation.

DATA SYNTHESIS

Wilson's disease, an inherited disorder of copper metabolism, is fatal if untreated. The chelating drugs penicillamine and trientine have been the mainstay of therapy; however, adverse reactions of chelators often interfere with successful treatment. Recently, zinc acetate was approved in the US for maintenance therapy in patients initially treated with a chelating agent. Although studies evaluating large populations are lacking zinc therapy has demonstrated exceptional safety and efficacy over a period of 40 years. Zinc acetate can be used during pregnancy and for the treatment of presymptomatic patients, although data do not support its use as monotherapy in patients with acute neurologic or hepatic disease.

CONCLUSIONS

Zinc acetate is an effective maintenance therapy for patients with Wilson's disease. Negligible toxicity, compared with that of previously approved treatments, is a major advantage.

Case report: concordant traumatic brainstem contusion delayed diagnosis in a young man with Wilson's disease

Wilson's disease is a hereditary autosomal recessive disorder of copper metabolism. The corresponding gene locus has been localized on the long arm of chromosome 13. Three different clinical variants of the disease can be distinguished: hepato-cerebral, abdominal/hepatic, and central nervous type. The heterogeneity of symptoms can cause problems in differential diagnosis, especially when another concordant disorder can also explain the pathogenesis of symptoms. The case report of a young man who suffered from brainstem contusion demonstrates the possibilities of misinterpretation because presenting symptoms could be attributed either to traumatic brain injury followed by adjustment disorder or Wilson's disease. Clinical signs included leftsided hemiparesis, bilateral gaze direction nystagmus, marked dysarthria with consecutive pervasive mutism, choreo-athetoid movements, spasmodic torticollis and diplopia dependent on gaze direction. Slit lamp examination showed Kayser-Fleischer's corneal ring. EEG- and computer assisted tomography investigations revealed non-specific findings. The patient was treated with D-Penicillamine. Alternative treatment with oral zinc preparations is discussed.

WILSON'S DISEASE (A report of two cases)

Two cases of Wilson's disease are reported. First case presented with fulminant hepatic failure and had a fatal outcome. The second had an insiduous onset, neurological manifestations, and is progressing satisfactorily on zinc therapy. Problems in diagnosis and treatment are highlighted.

Oral zinc as initial therapy in Wilson's disease: two years of continuous treatment in a 10-year-old child

Two years of continuous therapy promoted a significant overall amelioration in a 10-year-old boy affected by an hepatic form of Wilson's disease in which zinc sulphate was the sole therapy. In particular, liver function returned to normal and hepatic histology also improved. The parameters characterizing copper metabolism were kept under good control, and a decrease in copper concentration was found in both erythrocytes and liver. The copper balance study performed during the 25th month of treatment showed that oral zinc was still efficiently inhibiting the intestinal absorption of copper. No side effects have been reported so far.

Orthotopic liver transplantation in liver-based metabolic disorders

The efficacy of orthotopic liver transplantation (OLT) in the management of more common liver-based metabolic disorders associated with severe liver damage, alpha-1-antitrypsin deficiency (PIZZ), Wilson disease and tyrosinaemia has been demonstrated and indications defined. An early mortality in excess of 15% and finite resources limit its use. Phenotypic heterogeneity make the precise indication in other disorders less certain. In disorders in which endstage liver disease is less frequent such as cystic fibrosis, haemochromatosis and galacosaemia it has been a very effective therapy. It has been used with encouraging results in disorders in which the liver is structurally normal such as Crigler-Najjar type I, primary hyperoxaluria type I and primary hypercholesterolaemia. In these it should be performed before there is permanent damage to brain, kidneys or heart. OLT in the short term prevents hyperammonaemic coma in urea cycle defects and may prevent extrahepatic disease in glycogen storage disease type IV. Its limitation in reversing all metabolic effects in these and other disorders is discussed. It is ineffective in protoporphyria or Niemann Pick disease type II (Sea Blue Histiocyte syndrome) in which the transplanted liver acquires the lesions of the initial disorder and extrahepatic features progress. Early referral provides optimum circumstances to assess the benefits of OLT as compared with those of other forms of management and to achieve transplantation at the ideal time. The place of OLT in management will require constant review as metabolic disorders are better defined, new forms of therapy evolve and as techniques of liver transplantation and modes of immunosuppression improve.