text: （2）T和B细胞均缺如SCID（T-</sup>B-</sup>SCID）：①RAG-1/RAG-2缺陷致T-B-SCID为重组活化基因-1（RAG-1）或RAG-2突变所致，婴儿期即发病，外周血T和B细胞计数均明显减少但NK活性正常或升高11p13编码VDJ基因重组酶的RAG1/RAG2突变，使T细胞受体（TCR）和B细胞表面免疫球蛋白（SIg）的VDJ结构重组发生障碍，患者外周血T、B细胞均减少，患儿在生后2～3个月即发生严重的复发性感染。
entities.entity: B细胞
entities.label: bod
entities.entity: SCID
entities.label: dis
entities.entity: SCID
entities.label: dis
entities.entity: RAG-1/RAG-2缺陷
entities.label: dis
entities.entity: T-B-SCID
entities.label: dis
entities.entity: 重组活化基因-1
entities.label: bod
entities.entity: RAG-1
entities.label: bod
entities.entity: RAG-2
entities.label: bod
entities.entity: 血T和B细胞计数
entities.label: ite
entities.entity: 外周血T和B细胞计数均明显减少
entities.label: sym
entities.entity: NK活性
entities.label: ite
entities.entity: 但NK活性正常或升高
entities.label: sym
entities.entity: 11p13编码VDJ基因重组酶
entities.label: bod
entities.entity: RAG1
entities.label: bod
entities.entity: RAG2
entities.label: bod
entities.entity: T细胞受体
entities.label: bod
entities.entity: TCR
entities.label: bod
entities.entity: B细胞表面免疫球蛋白
entities.label: bod
entities.entity: SIg
entities.label: bod
entities.entity: VDJ
entities.label: bod
entities.entity: 血T、B细胞
entities.label: bod