目的 通过对孕妇羊水进行染色体核型、荧光原位杂交(fluorescence in situ hybridization,FISH)分析,探讨两者联合检测在诊断罗伯逊易位型21-三体中的应用价值.方法 为2010年1月至2011年12月进行产前诊断的孕妇抽取羊水,经体外细胞培养后进行G显带染色体核型分析.对发现的5例罗伯逊易位采用FISH检测间期细胞13、18、21及X/Y的染色体数目,并分析孕妇及其丈夫外周血染色体核型.结果 两个胎儿父母外周血染色体核型正常,其中一个胎儿羊水染色体核型为46,XY,rob(21；21)(q10;q10),FISH检测提示其为21-二体,另一个胎儿核型为46,XY,rob(14;21)(q10；q10),FISH检测证实其为21-三体.另外3个胎儿母亲外周血染色体核型分别为45,XX,rob(14;21)(q10;q10)、45,XX,rob(15;21)(q10;q10)、45,XX,rob(21; 22) (q10; q10),其羊水染色体核型分别为46,XX,rob(14;21)(q10;q10)、46,XY,rob(15;21) (q10;q10)、46,XX,rob(21;22)(q10;q10).FISH检测证实其均为21-三体.结论 染色体核型分析结合FISH检测有助于明确罗伯逊易位型21-三体的诊断,但FISH检测同源罗伯逊易位型21-三体征有一定局限性.%Objective To assess the value of fluorescence in situ hybridization (FISH) combined with chromosomal analysis for the detection of Robertsonian translocation type trisomy 21 in amniotic fluid cells.Methods Amniotic fluid samples from pregnant women requesting prenatal diagnosis were cultivated.Metaphase cells were prepared for G-banding karyotype analysis.For the 5 Robertsonian translocation type trisomy 21,interphase nuclei from amniotic fluid and parental peripheral blood cells were prepared for FISH analysis.Results In 2 cases,analysis of parental peripheral blood cells showed normal karyotypes.FISH analysis of amniotic fluid cells indicated that one sample had two copies of chromosome 21,which has a 46,XY,rob(21 ; 21) (q10 ; q10) karyotype,whilst another had trisomy 21 by FISH,which has a 46,XY,rob (14;21) (q10;q10) karyotype.For the remaining three samples,analysis of parental peripheral blood cells indicated that their karyotypes were 45,XX,rob(14;21)(q10;q10),45,XX,rob(15;21)(q10;q10) and 45,XX,rob(21;22) (q10;q10),whilst the karyotypes of amniotic fluid cells were 46,XX,rob(14;21) (q10;q10),46,XY,rob(15;21)(q10;q10) and46,XX,rob(21;22)(q10;q10),respectively.Conclusion Combined FISH and chromosomal analysis is an efficient method to detect non-homologous Robertsonian translocation type trisomy 21.However,FISH has limited ability to detect homologous Robertsonian translocation type trisomy 21.
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