进行性家族性肝内胆汁淤积症2型患儿的基因诊断

Genetic diagnosis of progressive familial intrahepatic cholestasis type 2

目的探讨进行性家族性肝内胆汁淤积症2型(PFIC2)临床特点和基因诊断的临床意义。方法采用多聚酶链反应(PCR)和DNA直接测序方法,检测6例疑似PFIC2患儿编码胆盐输出泵(BEPS)蛋白ABCB11基因的27个外显子,新发现的突变用SIFT、PolyPhen-2、SNPs&GO软件进行致病性预测;回顾性分析患儿的临床资料。结果共检测到4种致病基因突变:p.R928*、p.E554K、p.R575Q、p.Y337H,其中后3种为新发现的突变;经预测3种新发现的突变均可导致疾病。最终2例患儿符合PFIC2基因诊断。2例患儿均于出生1个月内发病,表现为黄疸,肝脾肿大,偶有烦躁不安。血清总胆红素水平升高,并以直接胆红素为主,γ谷酰转肽酶(GGT)<100 U/L,总胆汁酸升高。结论基因诊断有助确诊PFIC2。

Objectives To investigate the clinical features of progressive familial intrahepatic cholestasis type 2 （PFIC2） and to illustrate the importance of genetic diagnosis. Methods The mutations in 27 exons of ABCBll encoding bile salt export pump （BSEP） were identified using polymerase chain reaction （PCR） and direct DNA sequencing in 6 children with suspected PFIC2. The pathogenicity of the newly identified mutations were predicted by SIFT, PolyPhen-2, SNPs＆GO software. The clini- cal features and laboratory examinations were reviewed. Results Four disease-causing mutations, p.R928＊, p.E554K, p.R575Q and p.Y337H were identified, and the last three mutations were novel. These three kinds of novel mutations can cause the disease. Two children with genetic diagnosis had such manifestations as onset within a month after birth, jaundice, hepatosplenomegaly, upset, increased levels of total bilirubin and direct bilirubin, GGT〈100 U/L and high levels of total bile acid. Conclusions Genetic diagnosis is a potent tool for clinical diagnosis of PFIC2.