Clinical and genetic analysis of pediatric patients with Wilson disease.

BACKGROUND/AIMS: Wilson disease (WD, MIM# 277900) is an autosomal recessive disorder of copper transport resulting from the defective function of a copper transporting P-type ATPase. Detecting mutations and single nucleotide polymorphisms (SNPs) of the ATP7B gene in Turkish pediatric WD patients (n=32) and controls (n=52) is the aim of this research. MATERIALS AND METHODS: For screening mutations and SNPs of the ATP7B gene, sequencing was performed. RESULTS: Mutations were determined in the ATP7B gene in 23 out of the 32 pediatric patients. The mutation detection rate in the ATP7B gene of the pediatric Turkish WD patients was 71.875%. Fifteen different mutations were determined in the ATP7B gene. These mutations were distributed throughout the ATP7B gene and were as follows: 2 deletion, 1 insertion, 3 nonsense, and 9 missense mutations. Four of these, including c.3111delC (1 deletion) and c.2363C>T, c.3733C>A, and c.3451C>T (3 missense) mutations, were detected in the Turkish WD patients. Eleven polymorphisms were detected in both groups. Among these, c.3727G>A (SNP) was reported in the Wilson Disease Mutation Database by our group. Nine out of the thirty-two pediatric Turkish WD patients had no mutations in the ATP7B gene. CONCLUSION: To find the cause of WD in pediatric patients who have no mutation in ATP7B, additional research is necessary.

Functional characterization of new mutations in Wilson disease gene (ATP7B) using the yeast model.

The Wilson disease gene, a copper transporting ATPase (Atp7b), is responsible for the sequestration of Cu into secretory vesicles, and this function is exhibited by the orthologous Ccc2p in the yeast. In this study, we aimed to characterize clinically relevant new mutations of human ATP7B (p.T788I, p.V1036I and p.R1038G-fsX83) in yeast lacking the CCC2 gene. Expression of human wild type ATP7B gene in ccc2Δ mutant yeast restored the growth deficiency and copper transport activity; however, expression of the mutant forms did not restore the copper transport functions and only partially supported the cell growth. Our data support that p.T788I, p.V1036I and p.R1038G-fsX83 mutations cause functional deficiency in ATP7B functions and suggest that these residues are important for normal ATP7B function.

Mutation analysis of ATP7B gene in Turkish Wilson disease patients: identification of five novel mutations.

Wilson disease is an autosomal recessive disorder of copper metabolism caused by mutations in the ATP7B gene that encodes a P-type copper transporting ATPase. The aim of this study was to screen and detect mutations of the ATP7B gene in unrelated Turkish Wilson disease patients (n = 46) and control group (n = 52). Mutations were screened and detected by DNA sequencing. 30 out of 46 patients had mutations. 24 different Wilson disease related mutations were identified in those patients. The distribution of mutations in ATP7B gene was as follow: 17 missense, 3 nonsense, 1 silent, 3 frameshift (1 insertion, 2 deletion). None of them were not found in the control group. Five out of 24 mutations were found to be novel. Four of them were missense (c.2363C > T, c.3106G > A, c.3451C > T, c.3733C > A). The last one was deletion (c.3111delC). 10 single nucleotide polymorphisms (SNPs) given in the literature were found in both control and patients groups. Moreover one new polymorphism in exon 18 (c.3727G > A) not reported previously was discovered in both groups. It was striking that most of the mutations were found in exons 8, 12-14. This is the first study covering Turkish Wilson disease patients and control groups for mutation screening in all the coding regions of ATP7B gene by DNA sequencing method and adding five new mutations and one polymorphism into the HUGO Wilson disease mutation database.