中国北方汉族家族性肺结节病家系全外显子组测序分析

Whole exome sequencing and analysis of a Chinese family with familial pulmonary sarcoidosis

目的分析一个北方汉族家族性肺结节病家系中患者及健康成员的临床特征和全外显子组检测结果,寻找可能参与结节病致病机制的基因及突变位点。方法2016年11月在北京协和医院呼吸科确诊的2例中国北方汉族肺结节病患者为同一家族连续2代,纳入该家系的3例肺结节病患者及1名健康成员,其中男2例,女2例,发病年龄23~69岁,先证者为Ⅱ-6。通过临床特征、影像学及病理结果确诊结节病,并对家族史等临床资料进行收集。采集全血样本,完成全外显子组测序并通过ExAC、SIFT、Polyphenv2、Metascape数据库进行致病性分析和基因注释分析。结果全外显子组检测发现27个基因在数据库中提示致病性较高,ZC3H12A、BCR、C5AR2及INHBB基因在Metascape数据库的基因注释为"细胞分泌负性调控",其中ZC3H12A基因可负性调控辅助性T细胞17(Th17细胞)分化,可能参与结节病发病的免疫进程。经Sanger一代测序验证,发现该家系3例患者均出现ZC3H12A基因c.1361 A>G突变,而健康成员不出现突变。结论家族性肺结节病患者由于遗传因素导致机体的免疫应答发生改变,是结节病的致病机制之一。全外显子组检测及基因功能分析发现,该家系中Ⅱ-2、Ⅱ-6及Ⅲ-1肺结节病患者均在ZC3H12A基因的同一位点发生突变,该基因可参与肺结节病发病机制中Th17细胞的分化,可能是该家族性肺结节病患者的致病基因。

Objective To analyze the clinical features and the results of the whole exome sequencing(WES)of a Chinese family containing both pulmonary sarcoidosis patients and healthy members,and to find potent genes and variants that may be involved in the pathogenesis of sarcoidosis.Methods Three patients with pulmonary sarcoidosis and 1 healthy member was included from a Chinese Han family in the north of China diagnosed in November 2016,which characterized as 2 consecutive generations including 2 males and 1 female,aged from 23 to 69 years old.The proband isⅡ-6.Pulmonary sarcoidosis was diagnosed by clinical features,imaging and pathological findings,and clinical data such as family history were collected.Whole blood samples were taken and WES(Illumina NovaSeq S2)was performed.The pathogenicity analysis and gene annotation analysis were performed by ExAC,SIFT,Polyphenv2,Metascape databases.Results It was found that 27 genes were highly pathogenic in the database filtering result.After gene annotation analysis,we found that ZC3H12A gene can negatively regulate the differentiation of Th17 cells,which may be involved in the onset of pulmonary sarcoidosis.Sanger sequencing confirmed the c.1361 A>G variant in 3 sarcoidosis patients but normal in healthy member.Conclusions In patients with familial pulmonary sarcoidosis,the genetic background could regulate immune response which is one of the pathogenic mechanisms of sarcoidosis.The whole exome test and gene ontology analysis showed thatⅡ-2,Ⅱ-6 andⅢ-1 pulmonary sarcoidosis patients in this family were all shared the same variant on ZC3H12A gene,which played a pivotal role in differentiation of Th17 cells and is a potent pathogenesis gene in this Chinese pulmonary sarcoidosis family.