Molecular diagnosis of Wilson disease

Wilson disease (WD) is caused by mutations in the ATP7B gene. The diagnosis is based on clinical and biochemical criteria but these are increasingly recognized to have low sensitivity. Genetic diagnosis is considered impractical due to the large coding region of the ATP7B gene and extreme diversity of mutations. We assessed the feasibility and utility of genetic diagnosis in WD. The coding region of the ATP7B gene was scanned by single-stranded conformation polymorphism (SSCP) analysis in 6 cases in whom the diagnosis of WD was uncertain. In addition, we attempted molecular diagnosis in 26 WD patients of similar ethnicity but variable disease manifestations. In 6 individuals in whom the biochemical/clinical diagnosis was uncertain, DNA analyses were useful for assigning their status with respect to WD. Molecular diagnosis identified presymptomatic individuals in families affected by WD and assigned heterozygote carrier or wild-type status to individuals previously diagnosed as affected. In 26 WD patients, 92% of disease alleles were identified. The most common mutations were H1069Q, L936X, and 2532delA representing 48, 10, and 8% of disease alleles, respectively. Three novel mutations were identified: Q898R, 3061(-1)g --> a, and 3972insC. Genetic diagnosis is feasible for WD. Greater application of molecular diagnosis should enable an appreciation of the full spectrum of WD phenotype that is not possible with currently available diagnostic criteria.