目的了解BCR/ABL阴性B系急性淋巴细胞白血病（B-ALL）患儿IKZF1基因拷贝数异常情况,并分析IKZF1基因拷贝数异常与该部分患儿预后的相关性。方法应用多重连接探针扩增（MLPA）技术检测180例初诊BCR/ABL阴性B-ALL患儿IKZF1基因拷贝数异常情况。根据有无IKZF1基因缺失将其分成两组：IKZF1缺失组和IKZF1正常组。回顾性分析IKZF1拷贝数缺失与BCR/ABL阴性B-ALL患儿预后的关系。结果 180例患儿中共有27例（15.0%）患儿发生了IKZF1缺失,其中IKZF1基因8个外显子全部缺失者4例,单纯1号外显子缺失者17例,4～7号外显子缺失者3例,2～7号外显子缺失者3例。IKZF1缺失组患儿初诊时白细胞水平及流式MRD-高危组患儿的比例明显高于IKZF1正常组;IKZF1缺失组患儿多发生在无特殊融合基因异常的BCR/ABL阴性患儿,且IKZF1基因缺失患儿易伴随出现11、8、5、7、21号等染色体的异常。Kaplan-Meier法分析显示,IKZF1缺失组无病生存率（DFS）明显低于IKZF1正常组（0.740±0.096 vs 0.905±0.034,P=0.002）。Cox法分析显示在排除了年龄、性别、初始WBC、初诊时脑脊液状态、泼尼松松试验反应情况、染色体核型后,IKZF1缺失仍不利于患儿的DFS（P〈0.05）。结论部分BCR/ABL阴性B-ALL患儿存在IKZF1缺失,IKZF1缺失为BCR/ABL阴性B-ALL患儿DFS的独立危险因素。
本研究从DNA双链断裂同源重组修复角度探讨UNC13D(秀丽新小杆线虫)基因参与Ⅲ型家族性噬血细胞性淋巴组织细胞增生症(familial hemophagocytic lymphohistiocytosis type 3,FHL3)的发病机制。利用DNA同源重组修复方法,检测正常对照组及UNC13D基因下调后DR-U2OS细胞同源重组修复率的变化情况,并研究此基因的相关功能。结果表明:下调DR-U2OS细胞的UNC13D基因表达后,同源重组修复率较正常对照组明显下降,且差异有统计学意义(P<0.05),提示UNC13D编码蛋白Munc13-4不仅参与到细胞毒颗粒的胞吐过程中,而且在DNA双链断裂修复中也起作用。结论:UNC13D基因突变可能通过抑制细胞毒颗粒的胞吐和降低DNA双链断裂后的同源重组修复率参与FHL3发病过程,这一研究结果为揭示FHL3的发病机制提供新的理论基础。
Fanconi anemia(FA),an X-linked genetic or autosomal recessive disease,exhibits complicated pathogenesis.Previously,we detected the mutated Dynein Axonemal Heavy Chain 2(DNAH2)gene in 2 FA cases.Herein,we further investigated the potential association between DNAH2 and the homologous recombination repair pathway of FA.The assays of homologous recombination repair,mitomycin C(MMC)sensitivity,immunofluorescence,and ubiquitination modification were performed in U2OS and DR-U2OS cell lines.In MMC-treated U2OS cells,the downregulation of the DNAH2 gene increased the sensitivity of cells to DNA inter-strand crosslinks.We also observed the reduced enrichment of FANCD2 protein to DNA damage sites.Furthermore,the ubiquitination modification level of FANCD2 was influenced by the deficiency of DNAH2.Thus,our results suggest that DNAH2 may modulate the cell homologous recombination repair partially by increasing the ubiquitination and the enrichment to DNA damage sites of FANCD2.DNAH2 may act as a novel co-pathogenic gene of FA patients.
