Adenosine deaminase deficiency with mosaicism for a "second-site suppressor" of a splicing mutation: decline in revertant T lymphocytes during enzyme replacement therapy
Adenosine deaminase deficiency with mosaicism for a "second-site suppressor" of a splicing mutation: decline in revertant T lymphocytes during enzyme replacement therapy
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DOI：
10.1182/blood.v99.3.1005
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发表时间：
2002-02-01
期刊：
影响因子：
20.3
通讯作者：
Hershfield, MS
中科院分区：
文献类型：
--
作者：
Arredondo-Vega, FX;Santisteban, I;Hershfield, MS
来自3个沙特阿拉伯家庭的4例患者由于腺苷脱氨酶（ADA）基因的最后剪接受体位点g.31701T> a的新型含子突变纯合性而延迟发生免疫缺陷。异常剪接使最后4个ADA氨基酸发生突变，并增加了43个残基“尾巴”，使蛋白质不稳定。在大肠杆菌中表达的突变型互补DNA （cDNA）的ADA活性为野生型cDNA的1%。年龄最大的患者，诊断时16岁，比他4岁的患病妹妹有更大的残余免疫功能和更少的红细胞脱氧腺苷核苷酸升高。他的T细胞和eb病毒（EBV） B细胞系ADA活性为正常的75%，ADA蛋白大小正常。来自这些细胞和他全血的DNA具有2个突变的ADA等位基因。两者都携带g.31701T>A，但其中一个获得了11个相邻碱基对g.31702-12的缺失，这抑制了异常剪接，并从野生型内含子11/外显子12连接处切除了一个不寻常的富含嘌呤的区域。在ADA替代治疗期间，ADA在T细胞中的活性和“第二位点”逆转等位基因的丰度显著下降。这一发现提出了一个与干细胞基因治疗相关的重要问题。(C) 2002年由美国血液病学会出版。
Four patients from 3 Saudi Arabian families had delayed onset of Immune deficiency due to homozygosity for a novel intronic mutation, g.31701T>A, in the last splice acceptor site of the adenosine deaminase (ADA) gene. Aberrant splicing mutated the last 4 ADA amino acids and added a 43-residue "tail" that rendered the protein unstable. Mutant complementary DNA (cDNA) expressed in Escherichia coli yielded 1% of the ADA activity obtained with wild-type cDNA. The oldest patient, 16 years old at diagnosis, had greater residual immune function and less elevated erythrocyte deoxyadenosine nucleotides than his 4-year-old affected sister. His T cells and Epstein-Barr virus (EBV) B cell line had 75% of normal ADA activity and ADA protein of normal size. DNA from these cells and his whole blood possessed 2 mutant ADA alleles. Both carried g.31701T>A, but one had acquired a deletion of the 11 adjacent base pair, g.31702-12, which suppressed aberrant splicing and excised an unusual purine-rich tract from the wild-type intron 11/exon 12 junction. During ADA replacement therapy, ADA activity in T cells and abundance of the "second-site" revertant allele decreased markedly. This finding raises an important issue relevant to stem cell gene therapy. (C) 2002 by The American Society of Hematology.