Abstract:

Abstrat：Objective　To investigate the value of amniocentensis combined with sequence analysis and karyotyping in prenatal daiagnosis of high-risk fetus with severe combined immunodeficiency disease. Methods　Seven patients with severe combined immunodeficiency disease were diagnosed by gene analysis from 2008 to 2010，including six cases of X-linked severe combined immunodeficiency disease and one case of Omenn syndrome.After detailed inquiry for medical history， seven pedigree trees were drawn， including 20 carriers of abnormal genes.From 2008 to 2011， seven specimens of amniotic cell gotten by amniocentensis were collected from seven high-risk pregnant women with abnormal gene during 18 to 20 gestational weeks.IL-2RG or RAG1 gene was amplified by polymerase chain reaction （PCR） from DNA of amniotic cell gotten and sequencing was performed directly on the PCR products in forward and reversely. Karyotyping was performed in amniotic cell gotten cultivated by orthotope slice and G band staining.Gene analysis and evaluation of immune function were reexamined in high-risk fetus after delivery. Results　Amniocentensis and culture of amniotic cell gotten all successed in seven fetuses. Result of gene analysis and karyotyping showed that three male fetuses and two female fetuses were normal and two male fetuses were defective.Abnormity of IL-2RG gene was confirmed in the two defective fetuses. After delivery， the result of gene analysis and evaluation of immune deficiency was the same with that of prenatal diagnosis. Conclusion　Amniocentensis and karyotyping are qualified for prenatal diagnosis of severe combined immunodeficiency disease for its reliability，safety and less cost.

Key words: amniocentensis, prenatal diagnosis, severe combined immunodeficiency disease, karyotyping

摘要：

探讨羊膜腔穿刺结合基因序列和染色体核型分析在严重联合免疫缺陷（SCID）高危儿产前诊断中的意义。方法　2008—2010年重庆医科大学附属儿童医院基因诊断明确的7例SCID患儿，其中6例X连锁SCID、1例Omenn综合征。追问病史，建立7个SCID家系图谱，确诊20个异常基因携带者。对其中7个携带异常基因的高危孕妇于孕18～20周经羊膜腔穿刺抽取羊水，部分羊水经离心后，提取羊水细胞DNA，经PCR扩增IL-2RG或RAG1基因，扩增PCR产物进行双向序列重复测定。此外对羊水中胎儿脱落细胞进行培养，采用原位制片、G带染色技术进行染色体核型分析。产后采集高危儿外周血重新进行基因分析，并进行免疫功能评估。结果　全部病例穿刺均成功，羊水细胞培养成功率100%。基因和染色体核型分析结果显示，3例为正常男性胎儿，2例为正常女性胎儿，2例为男性缺陷胎儿。2例男性缺陷胎儿均为IL-2RG基因突变。除2例缺陷胎儿行人工流产术外，5例SCID高危儿均顺利出生，产后基因分析结果均正常，与产前结果相同。随访免疫功能均正常。结论　羊膜腔穿刺结合基因和染色体核型分析在SCID的产前诊断中是一项成熟有效的操作技术。