Wilson disease is an inherited autosomal recessive disorder of hepatic copper metabolism leading to copper accumulation in hepatocytes and in extrahepatic organs such as the brain and the cornea. Originally Wilson disease was described as a neurodegerative disorder associated with cirrhosis of the liver. Later, Wilson disease was observed in children and adolescents presenting with acute or chronic liver disease without any neurologic symptoms. While diagnosis of neurologic Wilson disease is straightforward, it may be quite difficult in non-neurologic cases. Up to now, no single diagnostic test can exclude or confirm Wilson disease with 100% certainty. In 1993, the gene responsible for Wilson disease was cloned and localized on chromosome 13q14.3 (MIM277900) (1, 2). The Wilson disease gene ATP7B encodes a P-type ATPase. More than 200 disease causing mutations of this gene have been described so far (3). Most of these mutations occur in single families, only a few are more frequent (like H1069Q, 3400delC and 2299insC in Caucasian (4-6) or R778L in Japanese (7), Chinese and Korean patients). Studies of phenotype-genotype relations are hampered by the lack of standard diagnostic criteria and phenotypic classifications. To overcome this problem, a working party discussed these problems in depth at the 8th International Meeting on Wilson disease and Menkes disease in Leipzig/Germany (April 16-18, 2001). After the meeting, a preliminary draft of a consensus report was mailed to all active participants and their comments were incorporated in the final text.

Previous studies have failed to identify mutations in the Wilson's disease gene ATP7B in a significant number of clinically diagnosed cases. This has led to concerns about genetic heterogeneity for this condition but also suggested the presence of unusual mutational mechanisms. We now present our findings in 181 patients from the United Kingdom with clinically and biochemically confirmed Wilson's disease. A total of 116 different ATP7B mutations were detected, 32 of which are novel. The overall mutation detection frequency was 98%. The likelihood of mutations in genes other than ATP7B causing a Wilson's disease phenotype is therefore very low. We report the first cases with Wilson's disease due to segmental uniparental isodisomy as well as three patients with three ATP7B mutations and three families with Wilson's disease in two consecutive generations. We determined the genetic prevalence of Wilson's disease in the United Kingdom by sequencing the entire coding region and adjacent splice sites of ATP7B in 1000 control subjects. The frequency of all single nucleotide variants with in silico evidence of pathogenicity (Class 1 variant) was 0.056 or 0.040 if only those single nucleotide variants that had previously been reported as mutations in patients with Wilson's disease were included in the analysis (Class 2 variant). The frequency of heterozygote, putative or definite disease-associated ATP7B mutations was therefore considerably higher than the previously reported occurrence of 1:90 (or 0.011) for heterozygote ATP7B mutation carriers in the general population (P < 2.2 × 10(-16) for Class 1 variants or P < 5 × 10(-11) for Class 2 variants only). Subsequent exclusion of four Class 2 variants without additional in silico evidence of pathogenicity led to a further reduction of the mutation frequency to 0.024. Using this most conservative approach, the calculated frequency of individuals predicted to carry two mutant pathogenic ATP7B alleles is 1:7026 and thus still considerably higher than the typically reported prevalence of Wilson's disease of 1:30 000 (P = 0.00093). Our study provides strong evidence for monogenic inheritance of Wilson's disease. It also has major implications for ATP7B analysis in clinical practice, namely the need to consider unusual genetic mechanisms such as uniparental disomy or the possible presence of three ATP7B mutations. The marked discrepancy between the genetic prevalence and the number of clinically diagnosed cases of Wilson's disease may be due to both reduced penetrance of ATP7B mutations and failure to diagnose patients with this eminently treatable disorder.

Questions addressing the diagnosis, treatment, and follow-up of WD in children were formulated by a core group of ESPGHAN members. A systematic literature search on WD using MEDLINE, EMBASE, Cochrane Database from 1990 to 2016 was performed focusing on prospective and retrospective studies in children. Quality of evidence was assessed according to the GRADE system. Expert opinion supported recommendations where the evidence was regarded as weak. The ESPGHAN core group and ESPGHAN Hepatology Committee members voted on each recommendation, using the nominal voting technique.

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