血友病A（Hemophilia A, HA)是由人凝血因子VIII基因（F8）突变所致，占血友病病人数的80%~85%，重型患者常可致残甚至危及生命。目前针对HA主要采取FVIII制剂替代治疗，但该疗法价格昂贵且长期输注存在一定风险。HA一直被认为是最有可能实现基因治疗的遗传病之一，但是目前尚无有效的基因治疗策略。F8长达186kb，已报道的突变多达2700多种。但是对于重型HA来说，约一半的患者都是由内含子22倒位突变所致。我们发现在这类病人中，虽然倒位的片段长达600kb，但是导致无法连续转录的F8编码序列只有627bp。由此我们提出一种针对内含子22倒位型重型HA的基因原位修复策略，即通过基因打靶的方式将这一小段编码序列原位添加进去。联合我们已建立的人诱导多潜能干细胞（iPSC）、干细胞基因打靶以及TALEN技术，验证这种原位修复策略的可行性，为HA提供有效的基因治疗方案。

Hemophilia A (HA) is the most common recessive X-linked genetic disorder with coagulation problems, which is caused by the defect of the coagulation factor VIII gene (F8). Severe HA is usually disabling and even lethal under some conditions. Clinically the HA patients are usually treated with repeated intravenous infusion of the clotting factor concentrate. For its costliness and the potential risk of infection and immune response, the treatment is really a financial and physiological incubus for HA patients. HA has long been considered to be a particularly significant target for gene therapy, but there is no cure for it so far. The F8 gene is 186 kb long with 26 exons encoding a 9 kb mRNA, and more than 2700 different types of mutation have been reported. However, about half of severe haemophiliacs are caused by an intron 22 inversion mutation. Although this mutation involves an inverted fragment of 600 kb, only 627 bp of coding sequence is dissociated from the F8 gene. We raise a gene therapy strategy for this common and severe type of HA, aiming to target this 627 bp of coding sequence at the intron 22-inverted F8 locus for in situ gene correction. Based on our established technologies of iPSC, gene targeting of stem cells and TALEN, we are trying to verify the feasibility of this strategy, providing effective method for HA gene therapy.