ATP7A基因变异所致Menkes病患儿3例的临床及遗传学分析

Clinical and genetic analysis of three children with Menkes disease due to variants of ATP7A gene

目的探讨3例ATP7A基因变异所致Menkes病患儿的临床特征与遗传学病因。方法选取2020年1月至2022年7月于广东医科大学附属医院儿童医学中心就诊的3例Menkes病患儿作为研究对象。收集3例患儿的临床资料,采集3例患儿及其父母和患儿1姐姐的外周血样,对患儿进行全外显子组测序(WES),用Sanger测序与拷贝数变异测序(CNV-seq)对候选变异进行家系验证,并对其进行生物信息学分析。结果患儿1为1岁4月龄的男性,患儿2和3为1岁10月龄的同卵男性双胎。3例患儿均表现为发育落后及癫痫发作。WES检测提示患儿1携带ATP7A基因c.3294+1G>A杂合变异,经Sanger测序验证其父母与姐姐均未携带该变异,提示为新发变异;患儿2和3携带c.77266650_77267178del拷贝数缺失变异,经CNV-seq验证,其母亲携带相同变异,父亲未见该变异。经检索HGMD、OMIM及ClinVar等数据库,ATP7A基因c.3294+1G>A变异为已知致病变异;在1000 Genomes、ESP、ExAC及gnomAD等数据库中未见正常人群的携带频率;根据美国医学遗传学与基因组学学会(ACMG)相关指南评级为致病性。c.77266650_77267178del拷贝数缺失变异涉及ATP7A基因的第8~9外显子,ClinGen在线系统对该变异的评分为1.8分,考虑为致病性。结论ATP7A基因c.3294+1G>A变异以及c.77266650_77267178del拷贝数缺失变异分别为患儿1、患儿2和3的遗传学病因。上述发现进一步丰富了Menkes病的变异谱,为患儿的临床诊断和遗传咨询提供了依据。

Objective To explore the clinical characteristics and genetic etiology of three children with Menkes disease.Methods Three children who had presented at the Children′s Medical Center,the Affiliated Hospital of Guangdong Medical University from January 2020 to July 2022 were selected as the study subjects.Clinical data of the children were reviewed.Genomic DNA was extracted from peripheral blood samples of the children,their parents and sister of child 1.Whole exome sequencing(WES)was carried out.Candidate variants were verified by Sanger sequencing,copy number variation sequencing(CNV-seq),and bioinformatic analysis.Results Child 1 was a 1-year-and-4-month male,and children 2 and 3 were monozygotic twin males aged 1-year-and-10-month.The clinical manifestations of the three children have included developmental delay and seizures.WES showed that child 1 has harbored a c.3294+1G>A variant of the ATP7A gene.Sanger sequencing confirmed that his parents and sister did not carry the same variant,suggesting that it was de novo.Children 2 and 3 had carried a c.77266650_77267178del copy number variation.CNV-seq results showed that their mother has carried the same variant.By searching the HGMD,OMIM and ClinVar databases,the c.3294+1G>A was known to be pathogenic.No carrier frequency has been recorded in the 1000 Genomes,ESP,ExAC and gnomAD databases.Based on the Standards and Guidelines for the Interpretation of Sequence Variants:A Joint Consensus Recommendation of the American College of Medical Genetics and Genomics(ACMG),the ATP7A gene c.3294+1G>A variant was predicted to be pathogenic.The c.77266650_77267178del variant has involved exons 8 to 9 of the ATP7A gene.ClinGen online system score for it was 1.8,which was also considered to be pathogenic.Conclusion The c.3294+1G>A and c.77266650_77267178del variants of the ATP7A gene probably underlay the Menkes disease in the three children.Above finding has enriched the mutational spectrum of Menkes disease and provided a basis for clinical diagnosis and genetic counseling.