New mutations in the Wilson disease gene, ATP7B: implications for molecular testing

Area of Science:

• Genetics
• Biochemistry
• Molecular Biology

Background:

• Wilson disease (WND) is an autosomal recessive disorder affecting copper transport.
• It results from mutations in the ATP7B gene, impacting copper excretion and leading to toxic copper accumulation in organs like the liver, brain, and kidneys.
• The disease exhibits significant genotypic and phenotypic variability.

Purpose of the Study:

• To identify and characterize novel mutations in the ATP7B gene in a cohort of 300 Wilson disease patients.
• To provide comprehensive documentation of genetic variants for improved DNA diagnosis and understanding of WND.
• To correlate identified mutations with the broad spectrum of clinical and biochemical presentations of Wilson disease.

Main Methods:

• Mutation analysis of the ATP7B gene was performed on 300 patients diagnosed with Wilson disease.
• New and previously reported mutations were identified across diverse ethnic groups.
• Variants were assessed for their disease-causing potential, with a focus on missense, silent, and intronic changes.

Main Results:

• A significant number of novel ATP7B mutations were identified in European white, Sephardic Jewish, Filipino, Lebanese, Japanese, and Taiwanese populations.
• Specific novel mutations include p.L217X, c.918_931, c.1073delG, c.3082_3085delAAGAinsCG, p.V536A, p.S657R, p.A971V, p.T974M, p.Q1004P, p.D1164N, p.E1173G, p.I1230V, p.M1359I, c.2355+4A>G, p.Q286X, p.G1149A, p.R1228T, p.D1267V, and p.A1328T.
• Twenty nucleotide substitutions, including six novel ones, were identified, causing silent amino acid changes or intronic alterations.

Conclusions:

• The identification of numerous novel ATP7B mutations underscores the genetic heterogeneity of Wilson disease.
• Comprehensive mutation documentation is crucial for accurate genetic diagnosis and understanding the genotype-phenotype correlations in WND.
• This research contributes to a better understanding of the molecular basis of Wilson disease and facilitates improved diagnostic strategies.