Truncating mutations in the Wilson disease gene ATP7B are associated with very low serum ceruloplasmin oxidase activity and an early onset of Wilson disease

Abstract

Abstract Background Mutations in the gene ATP7B cause Wilson disease, a copper storage disorder with a high phenotypic and genetic heterogeneity. We aimed to evaluate whether 'severe' protein-truncating ATP7B mutations (SMs) are associated with low serum ceruloplasmin oxidase activities and an early age of onset when compared to missense mutations (MMs). Methods The clinical phenotype of 59 genetically confirmed WD patients was analyzed retrospectively. Serum ceruloplasmin was measured by its oxidase activity with o-dianisidine dihydrochloride as substrate and immunologically. Results Thirty-nine patients had two MMs, 15 had the genotype SM/MM, and 5 patients had two SMs on their ATP7B alleles. Enzymatic and immunologic serum ceruloplasmin levels differed significantly between the three groups (P Conclusions In our German study cohort truncating ATP7B mutations were associated with lower ceruloplasmin serum oxidase levels and an earlier age of onset when compared to MMs. Measurement of serum ceruloplasmin oxidase might help to predict presence of truncating ATP7B mutations and might facilitate the mutation analysis.