分子生物学（张海红）1-绪论2014.pptVIP

* 我国也在1994年用导入人凝血因子Ⅸ基因的方法成功治疗了乙型血友病的患者。在我国用作基因诊断的试剂盒已有近百种之多。基因诊断和基因治疗正在发展之中。　　 * 由于腺苷脱氨酶(adenosine deaminase，ADA)缺陷，导致核苷酸代谢产物dATP的蓄积，使早期T细胞和B细胞发育停滞于pro-T/pro-B阶段，导致T细胞和B细胞的缺陷。为常染色体隐性遗传性疾病。 * ADA是一种氨基水解酶，参与嘌呤代谢过程，催化腺嘌呤核苷脱氨基变成肌苷。肌苷在嘌呤核苷磷酸化酶(PNP)作用下转化为次黄嘌呤，次黄嘌呤在次黄嘌呤鸟嘌呤磷酸核糖转化酶(HGPRT)作用下转变为磷酸肌苷或转化为尿酸排泄。编码ADA的基因位于第20号染色体长臂。大多数患儿ADA突变仅为CpG二核苷酸CT点突变，整个基因或部分基因缺失仅见于少数病例。 * SCID is a life-threatening syndrome of recurrent infections, diarrhoea, skin infections and failure to thrive that results from numerous molecular defects leading to severe T- and B-cell dysfunction and occasionally can affect natural killer (NK) cells. Without intervention, the T and B-cell dysfunction usually results in severe infection and death in children by age 2 years. Clinically, most patients present before age 3 months with unusually severe and frequent infections by common or opportunistic pathogens.? Children with SCID develop symptoms in the first two to seven months. Typically they fail to gain weight and do not grow normally. They may have persistent diarrhea, upper respiratory symptoms and a fungal infection of the mouth and diaper area that doesn’t respond to typical treatments or medicines given for these symptoms.A life threatening pneumonia can also be developed and often leads to the diagnosis of an immune system disorder. In normal individuals, this pneumonia does not lead to serious disease, but in SCID can be fatal if left untreated. Meningitis and bloodstream infections can also be seen.The most common treatment for SCID is bone marrow transplantation, which has been successful using either a matched related or unrelated donor, or a half-matched donor, who would be either parent. The half-matched type of transplant is called haploidentical. David Vetter, the original bubble boy, had one of the first transplantations but eventually died because of an unscreened virus in his newly transplanted bone marrow from his sister. Today, transplants done in the first three months of life