Distinct clinical courses according to presenting phenotypes and their correlations to ATP7B mutations in a large Wilson's disease cohort

Introduction and aims: Wide phenotypic and genotypic heterogeneities in Wilson's disease (WD) have been reported, hampering the study of their correlations. The goal of this study was to identify the factors related to these diversities. Methods: Clinical courses and molecular genetic characteristics were analysed in 237 unrelated Korean WD families. The average follow-up period was 8.2 ± 5.8 years. Results: Presenting phenotypes were classified as H1 (12.2%), H2 (42.4%), N1 (21.6%), N2 (0.4%), NX (0.4%), presymptomatic (22.4%) and other (0.4%), modifying the guidelines by Ferenci and colleagues. Age at presentation was youngest and cirrhosis was rarest in the presymptomatic group. Decompensated cirrhosis was the highest in the H1 group. Favourable outcome was rarest in the N1 group. Forty-seven (11 novel) ATP7B mutations were identified in 85% of the 474 alleles. Multiplex ligation-dependent probe amplification assays in ATP7B and analyses of ATOX1 and COMMD1 genes identified no additional mutations. Yeast complementation assays demonstrated functional perturbation of the seven novel missense mutants. Five major mutations, p.Arg778Leu, p.Ala874Val, p.Asn1270Ser, p.Lys838SerfsX35 and p.Leu1083Phe, accounted for 63% of the alleles. H1 was more common, age at presentation was younger and N1+N2+NX tended to be less common in patients with nonsense, frame shifting or splicing mutations than in those with missense mutations alone. Patients with both mutations in the transduction (Td) or the ATP hinge domain showed presymptomatic or hepatic manifestations but no neurological manifestation. Conclusions: The presenting phenotype strongly affects the clinical outcome of WD, and is related to the ATP7B mutation type and location, providing an evidence for genotype–phenotype correlations in WD.