STR-PCR分析诊断常见染色体三体及其亲源性、染色体不分离时期

目的]通过采用短串联重复序列结合聚合酶链反应(STR-PCR)技术对胎儿进行产前诊断以及对已知染色体21三体的病例进行检测,探讨STR-PCR技术诊断常见三体综合征,同时判断额外染色体的双亲来源以及染色体不分离发生时期.方法]收集了51个家系的174例样本,其中产前诊断组35个家系,包括18例单胎妊娠和17例多胎妊娠家系;已知为染色体21三体患者16个家系.采用STR-PCR技术,扩增21号染色体4个位点;18、13号染色体各3个位点,诊断这些染色体三体综合征,与染色体核型对照;并判断额外染色体双亲来源和染色体不分离发生时期.结果]检出18例完全型染色体三体综合征,包括21三体16例;18三体和13三体各1例,其中4例为产前诊断的胎儿.1例罗氏易位型和1例嵌合型21三体未能检出.14例21三体及1例18三体、1例13三体可确定额外染色体的亲代来源和不分离时期.结论]STR-PCR技术在诊断多种完全型染色体三体的同时,可判断额外染色体的亲源性及分析染色体不分离时期.但对嵌合型和易位型染色体异常的诊断有待改进.

Diagnosis of Common Trisomies and Identification of Parental Origins of Extra Chromosomes and Stages of Nondisjunction by STR-PCR Analysis

Objective]To investigate the technique of STR-PCR used in diagnosing common trisomies and identifying the parental origins of the extra chromosomes, as well as the stages of nondisjunction. Methods] Fifty-one families (totally 174 samples) were collected, in which 35 families were from prenatal diagnosis group (18 singleton and 17 multiple pregnancies), 16 were from the patients whose chromosomal karyotypes had already been confirmed as 21 trisomy. STR-PCR technique was used to amplify 4 loci on chromosome 21, 3 loci on chromosome 18 and 3 loci on chromosome 13 to diagnose those chromosomal trisomies as well as the parental origins of the extra chromosomes and the stages of nondisjunction. Results] Eighteen cases with typical trisomies were detected by STR-PCR, among them, there were sixteen trisomy 21, one trisomy 18 and one trisomy 13 respectively, in which 4 were fetuses from prenatal diagnosis. However, a Robertsonian translocation and a mosaic trisomy 21 could not be detected. Fourteen out of sixteen trisomy 21, one trisomy 18 and one trisomy 13, could be identified the parental origins of the extra chromosomes as well as the stages of nondisjunction. Conclusion ]STR-PCR technique is effective for diagnosing many common typical trisomies, meanwhile, the parental origins of extra chromosomes and the stages of nondisjunction can be identified. Nevertheless, for mosaic and translocation, this method is limited and should be improved.