2014年，对27岁的X-连锁慢性肉芽肿病(X-CGD)患者进行了使用MFGS-gp91phox逆转录病毒载体的干细胞基因治疗。患者的难治性感染得到了解决，而氧化酶阳性中性粒细胞在6个月内消失。基因治疗后32个月，患者发展为骨髓增生异常综合征(MDS)，并在幼稚细胞中鉴定到MECOM基因组中的载体整合。在基因治疗后12个月，MECOM基因组的载体整合能在大部分髓细胞中检测到。然而，在MDS发生之前，患者展现了正常的造血功能，这表明MECOM基因激活在克隆造血中起了作用，而爆发性转化很可能是在获得了额外的基因突变后出现的。在全基因组测序中，发现在肿瘤发生之前就发生了WT1肿瘤抑制基因的等位基因丧失，因此它可能是一个潜在的候选遗传突变。爆发细胞中的CYBB cDNA负链含有108个G-to-A突变，这表明在CD34阳性细胞的转导过程中发生了APOBEC3介导的高突变率。高突变率介导的氧化酶活性丧失可能促进了MECOM基因激活的克隆生存和增殖。我们的数据为X-CGD基因治疗中发展白血病的复杂机制提供了宝贵的见解。 由The American Society of Gene and Cell Therapy版权所有，Elsevier Inc.所有，保留所有权利。

Stem cell gene therapy using the MFGS-gp91phox retroviral vector was performed on a 27-year-old patient with X-linked chronic granulomatous disease (X-CGD) in 2014. The patient's refractory infections were resolved, whereas the oxidase-positive neutrophils disappeared within 6 months. Thirty-two months after gene therapy, the patient developed a myelodysplastic syndrome (MDS), and vector integration into the MECOM locus was identified in blast cells. The vector integration into MECOM was detectable in most myeloid cells at 12 months after gene therapy. However, the patient exhibited normal hematopoiesis until the onset of MDS, suggesting that MECOM transactivation contributed to clonal hematopoiesis, and the blast transformation likely arose after the acquisition of additional genetic lesions. In whole-genome sequencing, the biallelic loss of the WT1 tumor suppressor gene, which occurred immediately before tumorigenesis, was identified as a potential candidate genetic alteration. The provirus CYBB cDNA in the blasts contained 108 G-to-A mutations exclusively in the coding strand, suggesting the occurrence of APOBEC3-mediated hypermutations during the transduction of CD34-positive cells. A hypermutation-mediated loss of oxidase activity may have facilitated the survival and proliferation of the clone with MECOM transactivation. Our data provide valuable insights into the complex mechanisms underlying the development of leukemia in X-CGD gene therapy.Copyright © 2023 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.