儿童噬血细胞综合征穿孔素基因突变筛查及临床研究

Screening and clinical research into PRF1 gene mutations in children with hemophagocytic syndrome

目的了解穿孔素基因(PRF1)突变和序列变异在中国儿童噬血细胞综合征(HLH)中的发生情况,探讨基因突变型与临床表现之间可能的关系。方法应用聚合酶链反应(PCR)结合直接测序方法,对2006年1月至2008年5月在首都医科大学附属北京儿童医院治疗的临床诊断为HLH的30例患儿(HLH组)及50名新生儿(对照组)PRF1基因外显子编码区进行突变筛查。结果在3例HLH患儿的PRF1基因外显子编码区发现3个杂合错义突变,这3个突变均导致氨基酸改变(C102F、S108N和T450M),而在对照组中却未发现。1例患儿为复合杂合错义突变(S108N和T450M),从遗传学上可明确诊断为家族性HLH亚型2(FHL2);1个同义序列变异(Q540Q)在1例患儿中发现,而在对照组中未发现;在HLH组和对照组的PRF1基因编码区发现2个单核苷酸多态位点(SNP)(A274A、H300H),但这2个SNP的基因型频率在HLH组和对照组之间的分布差异无统计学意义(P均>0.05)。结论我国HLH患儿中存在PRF1基因突变,而突变位点(C102F和S108N)目前仅在中国患儿中发现。显示了我国HLH患儿PRF1基因突变具有自身的特点。对于无HLH家族史和起病年龄较晚的HLH患儿,也要考虑家族性HLH的可能。

Objective To investigate the prevalence of mutations and sequence variations of PRF1 gene in Chinese pediatric patients with hemophagocytic syndrome （HPS） and to explore the possible relationship between gene mutations and clinical manifestations. Methods Polymerase chain reaction （PCR） was performed on five pairs of primers for the coding exons and the flanking intron sequences of the PRF1 gene. PCR products sequencing was suhsequently applied to 30 pediatric patients with HLH and 50 controls. Results Three heterozygous mutations in coding region were found, which resuhed in amino acid change （CI02F, SI08N and T450M） in 3 patients. Those mutations were not detected in control subjects. One patient has compound heterozygous mutations （SI08N and T450M） in the PRF1 gene, which was clearly diagnosed as familial HLH type 2 （FHL2）. One synonymous sequence variant （Q540Q） was observed in one patient but not in the controls. Two SNPs （A274A, H3OOH） in coding region both in HLH patients and controls were detected, but the heterozygosity rate had no difference between the two groups. Conclusion PRF1 gene mutations exist in Chinese children with HLH, and the mutation loci of C102F and S108N only exist in Chinese children, which shows that the PRF1 gene mutations in HLH children in China have their own characteristics. The HLH children without familial HLH history or with late onset may have familial HLH.