Lebedev Igor N, Ostroverkhova Nadezhda V, Nikitina Tatyana V, Sukhanova Natalia N, Nazarenko Sergey A
Cytogenetics Laboratory, Institute of Medical Genetics, Tomsk Scientific Centre, Russian Academy of Medical Sciences, 634050 Tomsk, Russia.
Eur J Hum Genet. 2004 Jul;12(7):513-20. doi: 10.1038/sj.ejhg.5201178.
Cytogenetic analysis of reproductive wastage is an important stage in understanding the genetic background of early embryogenesis. The results of conventional cytogenetic studies of spontaneous abortions depend on tissue culturing and are associated with a significant cell culture failure rate. We performed interphase dual-colour FISH analysis to detect chromosomal abnormalities in noncultured cells from two different tissues-cytotrophoblast and extraembryonic mesoderm-of 60 first-trimester spontaneous abortions from which cells had failed to grow in culture. An original algorithm was proposed to optimize the interphase karyotype screening with a panel of centromere-specific DNA probes for all human chromosomes. The overall rate of numerical chromosomal abnormalities in these cells was 53%. Both typical and rare forms of karyotype imbalance were found. The observation of six cases (19%) of monosomy 7, 15, 21 and 22 in mosaic form, with a predominant normal cell line, was the most unexpected finding. Cell lines with monosomies 21 and 22 were found both in cytotrophoblast and mesoderm, while cells with monosomy 7 and 15 were confined to the cytotrophoblast. The tissue-specific compartmentalization of cell lines with autosomal monosomies provides evidence that the aneuploidy of different human chromosomes may arise during different stages of intrauterine development. The effect of aneuploidy on selection may differ, however, depending on the specific chromosome. The abortions also revealed a high frequency of intratissue chromosomal mosaicism (94%), in comparison with that detected by conventional cytogenetic analysis (29%; P<0.001). Confined placental mosaicism was found in 25% of the embryos. The results of molecular cytogenetic analysis of these cell culture failures illustrate that the diversity and phenotypic effects of chromosomal abnormalities during the early stages of human development are underestimated.
对生殖损耗进行细胞遗传学分析是了解早期胚胎发生遗传背景的重要阶段。自然流产的传统细胞遗传学研究结果依赖于组织培养，且细胞培养失败率较高。我们进行了间期双色荧光原位杂交分析，以检测来自60例孕早期自然流产的两种不同组织——细胞滋养层和胚外中胚层——的未培养细胞中的染色体异常，这些流产组织的细胞在培养中未能生长。我们提出了一种原始算法，用一组针对所有人类染色体的着丝粒特异性DNA探针优化间期核型筛查。这些细胞中染色体数目异常的总体发生率为53%。发现了典型和罕见的核型失衡形式。最意外的发现是观察到6例（19%）以镶嵌形式存在的7、15、21和22号染色体单体，其中正常细胞系占主导。21号和22号染色体单体的细胞系在细胞滋养层和中胚层中均有发现，而7号和15号染色体单体的细胞仅限于细胞滋养层。常染色体单体细胞系的组织特异性分隔提供了证据，表明不同人类染色体的非整倍体可能在子宫内发育的不同阶段出现。然而，非整倍体对选择的影响可能因具体染色体而异。与传统细胞遗传学分析检测到的频率（29%；P<0.001）相比，这些流产还显示出组织内染色体镶嵌现象的高频率（94%）。25%的胚胎中发现了局限性胎盘镶嵌现象。对这些细胞培养失败进行分子细胞遗传学分析的结果表明，人类发育早期染色体异常的多样性和表型效应被低估了。
