Studio del Promoter ATP7B. Ruolo potenziale nella variabilità fenotipica presente nella malattia di Wilson

Wilson disease (WD) is an autosomal recessive disorder of copper transport, characterized by decreased copper biliary exrection and reduced copper incorporation into ceruloplasmin. This results in copper overload and tissue damage. In the last years we have carried out mutation analysis in approximately 644 unrelated familes of mediterranean origin and identified 175 Wilson disease causing mutations. One of identified mutations –441_427del, a 15 nt mutation is the only diseasecausing defect detected in the promoter region of the ATP7B gene. Functional characterization assays revealed a 75% impairment in the promoter activity as compared to the normal control. Recently we have identified 8 new rare mutations in the promoter region of the gene detected in cis with two known promoter polymorphisms. Functional studies were performed with transient transfection of two cell lines HepG2 and SH-SY5Y and showed that promoter activity was different in the different analyzed constructs according to haplotype. These data suggest a potential role for promoter ATP7B gene polymorphisms to copper resistance and phenotypic variability in WD patients. In this study we propose to clarify the role of ATP7B gene promoter polymorphisms in Cu resistance using functional characterization assays of promoters carrying different combinations of detected polymorphisms.