Phenotype and genotype analysis of 55 children patients with Wilson's disease

Abstract

Objective: To understand the clinical phenotype and spectrum of ATP7B gene mutation in children with Wilson's disease (WD). Methods: A total of 55 cases diagnosed with WD at the Children's Hospital Affiliated to Nanjing Medical University from June 2012 to June 2018 were taken as the research subject. ATP7B gene point mutation was detected by direct sequencing after PCR amplification. Heterozygous mutation in children was discovered by sequencing. Furthermore, the long segment mutation of exon was analyzed by multiplex ligation-dependent probe amplification (MLPA). Results: All 55 WD children had varying degree of liver damage symptoms. Among them, 2 cases had combined neurological symptoms. The positive rates of K-F ring (21%), 24-hour urine copper (97.7%), and ceruloplasmin were all abnormal. The results of ATP7B gene had identified 8 homozygous, 41 compound heterozygous and 6 heterozygous in 55 cases. Direct sequencing method had detected ten cases of ATP7B heterozygotes. In addition, MLPA analysis showed that other allele in four cases had a deletion of the ATP7B gene exon. In all cases, 35 different ATP7B gene mutations were detected, including 23 missense mutations, 3 frameshift mutations, 4 nonsense mutations, 3 exon deletions and 2 splicing changes. The most common allele mutation was c.2333G > T/p.R778L in exon 8, with an allele frequency of 36.54%, followed by c.2975C > T/p.P992L in exon 13, with an allele frequency of 14.42%. Conclusion: ATP7B gene c.2333G > T/p.R778L and c.2975C > T/p.P992L mutations are the most common mutations in children with WD in China. WD patients report shows that there are three long deletion mutations in the exon of the ATP7B gene. For WD children whose DNA sequencing is heterozygous ATP7B gene, it is suggested to further use MLPA method to detect deletion mutations of exons.