Mutation spectrum of ATP7B gene in pediatric patients with Wilson disease in Vietnam.

Background: Wilson disease (WD) is caused by mutations in the copper-transporting P-type adenosine triphosphatase encoded by the ATP7B gene. In this study, we screened and identified the ATP7B mutations among unrelated Vietnamese pediatric patients. Methods: One-hundred-thirteen pediatric patients with clinically diagnosed WD were recruited. DNA samples were extracted from peripheral blood. Mutations in the ATP7B gene were identified by Sanger sequencing. Results: Approximately 98% of the clinically diagnosed WD patients carried ATP7B mutations. A total of 35 different ATP7B variants were detected, including five novel mutations (L658P, L792P, T977K, IVS4 + 1G > A and IVS20 + 4A > G). Remarkably, this study revealed that S105* was the most prevalent variant (32.27%), followed by L1371P (9.09%), I1148T (7.27%), R778L (6.36%), T850I (5.45%), V176Sfs*28 and IVS14-2A > G (4.55%). Most ATP7B mutations were located in the exon 2 (37.73%), exon 16 (10.00%), exon 8 (9.55%), exon 20 (9.09%), exon 10 and exon 18 (5.45%), exon 14 (5.00%), exon 13 and intron 14 (4.55%). We developed a streamlined procedure to quickly characterize mutations in the ATP7B gene in the Vietnamese children, starting with sequencing exon 2 and subsequently to exons 8,10,13-16,18, and 20 to allow quick diagnosis of clinically suspected patients. Conclusion: The mutational spectrum and hotspots of ATP7B gene in the Vietnamese population were fairly different from other East Asian populations. A streamlined procedure was developed to screen exon 2 in ATP7B gene among suspected WD patients to reduce genetically diagnostic cost, to facilitate early detection and intervention in countries with limited resources.

Biliary atresia combined Wilson disease identified by whole exome sequencing in Vietnamese patient with severe liver failure.

RATIONALE: Hepatobiliary diseases such as biliary atresia (BA), Wilson disease, and progressive familial intrahepatic cholestasis are common causes of morbidity and mortality in young children. Affected patients progress rapidly to end-stage cirrhosis and require liver transplantation or die. Mutations in many genes have been identified to play an important role in the pathogenesis of hepatobiliary diseases. PATIENT CONCERNS AND DIAGNOSIS: In this study, we identified mutations in an 8-year-old girl who had severe liver failure. The patient was first diagnosed with BA at 2.5 months of age and has undergone Kasai surgery to connect the umbilical cord and jejunum. After that, the patient suddenly had unusual developments with symptoms of jaundice, acute liver failure with hemolysis. She was tested and diagnosed with Wilson disease. INTERVENTIONS AND OUTCOMES: She was treated according to the regimen for a patient with Wilson disease but had abnormal progress leading to severe liver failure. Genetic analysis was performed by whole exome sequencing and Sanger sequencing methods. The genetic analysis revealed that the patient had a homozygous mutation (p.Gly17Glyfs77∗) in the KRT18 gene, a double heterozygous mutation (p.Ser105∗ and p.Pro992Leu) in the ATP7B gene, and a homozygous variant (p.Val444Ala) in the ABCB11 gene. In silico prediction of mutations indicated that these mutations are the cause of the severe liver failure in the patient. LESSON: This is a rare clinical case of a BA patient combined with Wilson disease. Our results suggested that whole exome sequencing is an effective diagnostic tool and emphasizes the importance of early diagnosis and appropriate management to save lives and prevent serious complications in the patient.

The role of p.Val444Ala variant in the ABCB11 gene and susceptibility to biliary atresia in Vietnamese patients.

ABSTRACT: Biliary atresia (BA) is the most serious type of obstructive cholangiopathy that occurs in infants. BA can be the cause of death in children under 2 years if untreated early. However, the etiology of the disease is not known. BA is considered to be the result of the destruction of the bile duct system including the accumulation of bile acids. The bile salt export pump, a transporter protein encoded by the ABCB11 gene, plays the main role in the exportation and accumulation of bile acids. The p.Val444Ala variant in this gene is known to be associated with many cholestatic diseases. However, to date no study have been performed to evaluate the association of this variant with susceptibility to the risk of BA. In this study, we aimed to identify the frequency of p.Val444Ala variant and the risk of BA in Vietnamese patients.The polymerase chain reaction (PCR)- restriction fragment length polymorphism method was used to determine the frequency of alleles c.1331T>C (p.Val444Ala, rs2287622) in the ABCB11 gene in 266 Vietnamese patients with BA and 150 healthy people. The gene segment containing the variant was amplified by PCR with specific primers, after that the PCR products were cut by HaeIII restriction enzyme and analyzed on agarose gel to determine the genotypes. The frequency of alleles was assessed statistically to determine the association between these alleles and the risk of disease in patients.In our study, the frequency of alleles c.1331T>C (p.Val444Ala, rs2287622) in the ABCB11 gene was investigated the first time in the patients with BA. The results showed that CC and TC genotypes were significantly different between BA patients and healthy people (P < .01), and the C allele was associated with an increased risk of BA (odds ratio = 2.47; 95% confidence interval: 1.84-3.32; P < .01). The initial results of clinical, biochemical, and genetic analysis in our study suggested that the p.Val444Ala variant in the ABCB11 gene may be a susceptibility factor for the disease in Vietnamese patients with BA. These results provided new insights into the role of this ABCB11 variant in the pathogenesis of BA.

Three novel mutations in the ATP7B gene of unrelated Vietnamese patients with Wilson disease.

BACKGROUND: Wilson disease (OMIM # 277900) is a autosomal recessive disorder characterized by accumulation of copper in liver and brain. The accumulation of copper resulting in oxidative stress and eventually cell death. The disease has an onset in a childhood and result in a significant neurological impairment or require lifelong treatment. Another serious consequence of the disease is the development of liver damage and acute liver failure leading to liver transplant. The disorder is caused by mutations in the ATP7B gene, encoding a P-type copper transporting ATPase. CASE PRESENTATION: We performed genetic analysis of three unrelated patients from three different Vietnamese families. These patients had clinical features such as numbness of hands and feet, vomiting, insomnia, palsy, liver failure and Kayser-Fleischer (K-F) rings and were diagnosed with Wilson disease in the Human Genetics Department, Vietnam National Children's Hospital. The entire coding region and adjacent splice sites of ATP7B gene were amplified and sequenced by Sanger method. Sequencing data were analyzed and compared with the ATP7B gene sequence published in Ensembl (ENSG00000123191) by using BioEdit software to detect mutations. CONCLUSIONS: In this study, five mutations in the ATP7B gene were found. Among of these, three mutations were novel: c.750_751insG (p.His251Alafs*19) in exon 2, c.2604delC (p.Pro868Profs*5) in exon 11, and c.3077 T > A (p.Phe1026Tyr) in exon 14. Our results of the mutations associated with Wilson disease might facilitate the development of effective treatment plans.