ATP7B Gene Exon Mutation Analysis In Wilson Disease Children

Background Wilson's disease(WD) is an autosomal recessive disorder characterized by decreased biliary copper excretion and reduced copper incorporation into ceruloplasmin.The defective biliary excretion leads to accumulation of copper in the liver with progressive liver damage and overflow to other organs,such as brain,cornea and renal.the disease gene ATP7B maps to chromosome 13q14.3,contains 21exons,and encodes a copper-transporting P-type ATPase. Defective ATP7B function results in hepatic copper accumulation, which leads to the hepatic and neurological features of Wilson's disease. The clinical characteristics of WD are diverse.The diagnosis is easily overlooked but if discovered early, effective treatments are available that will prevent or reverse many manifestations of this disorder. ATP7B mutations are scattered over the entire gene,and more than 500 mutations have been detected up-to-now.Objective To determine the hot point mutations of Chinese Wilson disease's gene and explore the methods and importance of gene diagnosis for WD patient. The genotype and phenotype correlation in patients with WD was analyzed.Method Genomic DNAfrom peripheral blood was collected for genetic analysis in 7 patients diagnosed clinically.Amplified 21 exons of ATP7B gene by Polymerase Chain Reaction(PCR). PCR products were analyzed by DNA direct sequencing. The relativity of the genotype and phenotype of ATP7B gene was investigated.Result Three of seven patients were found with mutations.One homozygous 918₉19insC mutation was found in exon 2 which had not benn reported before.The patient was manifestation of liver and kidney.one hererozyous C2332T mutation was found in exon 8,which had not been reported either in Chinese.The patient was presented as severe liver dysfunction and hemolytic anemia. One homozygous C2804T mutations was found in exon 12.The patient was presented as mild liver dysfunction .Four polymorphisms were found in six patients,all of which were reported. They are T1216G in exon 2,G1366C in exon 3,G2855A in exon 12 and T3419C in exon 16.Conclusion C2332T and 918₉19insC mutations were related to sever manifestation of liver and kidney,while C2804T mutation was a mild mutation . 918₉19insC had not been reported before.Patients who were not found mutations could not be ecluded .It was possible that unknown molecular defects may possibly lie deep inthe intronic regions or other regions.It suggest that DNA direct sequencing in WD patients could be used in diagnosing as a gend method.