Z Qiao, G Zhou, M Jiang

Abstract

Objectives: Wilson disease (WD), also known as hepato-lenticular degeneration, is an autosomal recessive inherited disorder of copper metabolism. The gene responsible for WD is located on chromosome 13 at 13q14.3, which encodes copper transporter P-type ATPase, namely ATP7B. Mutation of ATP7B is a genetic signal of highly risk suffering from WD. Here, we aim to analyse the hotspot of ATP7B mutations in WD patients from South China using Sanger sequencing. Methods: In this study, 50 healthy individuals and 32 identified WD patients were enrolled, who manifested with abnormal hepatic function including increased Alanine Transaminase (ALT) or Aspartate Transaminase (AST), and/or dyskinesia. The genomic locus of ATP7B of these patients were amplified by polymerase chain reaction (PCR), then sequenced via Sanger sequencing. Results: Genetic variations were found in all patients, including 17 mutations and nine SNPs, one of which (c.1757T>A) is novel. The most frequent mutations were P.778R>L (22.5%), P.770L>L (17.5%), and P.935T>M (10.0%). These mutations were mainly clustered in the exon 5, 8, 12, and 13 of ATP7B. Conclusions: Based on Sanger sequencing of ATP7B in this study, p.778R>L mutation clustered in the CU channel transmembrane domain consisted over 50% of ATP7B mutations, suggesting hotspots in South China and supplying a suitable strategy focusing on this hotspot for ATP7B screening in South China WD patients. The newly identified mutation, c.1757T>A, is deleterious based on an array of predictions and highly conserved upon comparison among different species. Furthermore, the c.1757T>A is classified as likely pathogenic variant according to American College of Medical Genetics (ACMG) guidelines (2015 Edition).