Familial screening of children with Wilson disease: Necessity of screening in previous generation and screening methods

Spectrum and classification of ATP7B variants with clinical correlation in children with Wilson disease

OBJECTIVES

To study the spectrum and classification of ATP7B variants in Iraqi children with Wilson disease by direct gene sequencing with clinical correlation.

METHODS

Fifty-five unrelated children with a clinical diagnosis of Wilson disease (WD) were recruited. Deoxyribonucleic acid was extracted from peripheral blood samples, and variants in the ATP7B gene were identified using next-generation sequencing.

RESULTS

Seventy-six deleterious variants were detected in 97 out of 110 alleles of the ATP7B gene. Thirty (54.5%) patients had 2 disease-causing variants (15 homozygous and 15 compound heterozygous). Twelve (21.8%) patients had one disease-causing variant and one variant of uncertain significance (VUS) with potential pathogenicity. Thirteen (23.6%) patients were carriers of a single disease-causing variant. The most frequent variants, c.3305T>C and c.956delC, were detected in 4 alleles each, followed by c.3741-3742dupCA and c.3694A>C, which were detected in 3 alleles each. Among the 76 variants, 42 were missense, 13 were stop-gain, 9 were frameshift, 1 was an in-frame deletion, and 11 were intronic variants. Notably, the globally common variant H1069Q was not detected in this study.

CONCLUSION

The mutational spectrum of ATP7B in the Iraqi population is diverse, despite the high rates of consanguinity. It differs from that of neighboring countries. We provided evidence for ten VUS to be reclassified as deleterious, raising questions about the diagnostic criteria for patients with higher Leipzig scores and a single deleterious variant.

Critical Points in the Methodology of Preparing Copper (II) Histidinate Injections and their Quality Assessment Applying Color Measurement

Copper (II) histidinate injection solution, applied in Menkes disease treatment, is characterized by low stability due to sensitivity to oxidation. The aim of this article was to determine the critical points of the injection preparation procedure, taking into account selection of appropriate packaging, determining the solution pH or application of an excess of L-histidine. In order to assess the stability of the Cu(His)2 complex, the spectrophotometric method (VIS: 400-800 nm), and the colorimetric method using a reflectance colorimeter were applied. The color changes observed using the CIELAB color system made it possible to determine: the differences in the observed color (ΔΕ) and the color chroma (C*) and hue (h°). It was found that the following parameters: λmax and ΔE enable fast and objective assessment of copper (II) histidinate injection solution quality. The advantage of the colorimetric method is the non-invasiveness of the analysis which is performed through the packaging material (transparent vial). The developed methodology of preparing Cu(His)2 injections in hospitals or community pharmacies guarantees their stability for at least 6 months, provided that the solution is stored at lower temperatures (2-8°C or 4°C).

Therapeutic strategies in Wilson disease: pathophysiology and mode of action

Wilson disease is a copper overload disease treatable with the chelators D-penicillamine and trientine to enhance urinary excretion or with zinc which predominantly inhibits absorption. By lifelong treatment a normal life expectancy and significant improvement of hepatic injury as well as neurologic manifestation is achievable. Here we evaluate the mode of action for effective therapy of Wilson disease. We postulate that there is no quantitative removal of copper from the liver possible. The therapeutic goal is the removal of toxic free copper (non-ceruloplasmin, but albumin bound copper). This is achievable by the induction of metallothionein which is accomplished by chelators and in particular by zinc. For control of therapy the option of a direct measurement of free copper would be preferable over the less reliable calculation of this fraction. A therapeutic challenge is still the full restoration of neurological deficits which can hardly be reached by the available chelators. Whether bis-choline-tetrathiomolybdate as intracellular copper chelator is an option has to be awaited. It is concluded that the goal of actual drug therapy in Wilson disease is the normalization of free copper in serum.

GENETIC DIAGNOSTICS AND CLINICAL FEATURES OF WILSON’S DISEASE IN CHILDREN

A disorder of copper metabolism at Wilson’s disease (WD), conditioned by a mutation of adenosine thriphospate P-type gene (ATP7B), results in irreversible changes in the liver and in the nervous system. Mortality is high at WD, but it is one of hereditary diseases, well subjected to the therapy. The disease is manifested in the early age, but its clinical course in children is symptomless that essentially complicates diagnostics. A single reliable method is genetic analysis for revealing mutations in ATP7B gene. The aim of the work was to analyze clinical manifestations and course of Wilson’s disease cases, genetically verified in children by detecting mutations of ATP7B gene. The research group included children of 6-17 years old with different injury degrees of the hepatobiliary system. According to results of the molecular-genetic analysis, the most spread allele variant of ATP7B gene (H1069Q) in Europe was confirmed in 10 patients of child age, including 4 cases of homozygosity. In 10 cases of the confirmed diagnosis of Wilson’s disease in child age in 100% (in all 10) of persons, a clinical manifestation was characterized by disorders from the hepatobiliary system, and only in 1 (10 %) – changes from the nervous system. At raising the level of transaminase in children, even at the normal bilirubin level and negative tests for viral hepatitis, it is recommended to carry out genetic testing for Wilson’s disease

Population screening and diagnostic strategies in screening family members of Wilson's disease patients

Wilson's disease (WD), also named hepatolenticular degeneration, is an autosomal-recessive disorder in which abnormal copper metabolism leads to copper excretion disorder and deposition in target organs. WD has a high mortality rate and disability rate, however, it is one of the treatable hereditary diseases. Irreversible tissue injury can be prevented if WD was diagnosed and treated before the development of clinical symptoms. Thus it is necessary to screen WD in the family members of the proband. First-degree relatives of a proband with WD should be screened. First-degree relatives should include the previous generation, siblings and the next generation. If available, genetic testing can be used as the primary screening method. Although the relatives of a proband are more likely to be patients with WD, the diagnosis should be based on sufficient evidence to avoid unnecessary lifelong treatment.