PDF(Pubmed)
Abstract：
Chromosomal mosaicism remains a perpetual diagnostic and clinical dilemma. In the present study, we detected two prenatal trisomy 9 mosaic syndrome cases by using multiple genetic testing methods. The non-invasive prenatal testing (NIPT) results suggested trisomy 9 in two fetuses. Karyotype analysis of amniocytes showed a high level (42%-50%) of mosaicism, and chromosomal microarray analysis (CMA) of uncultured amniocytes showed no copy number variation (CNV) except for large fragment loss of heterozygosity. Ultrasound findings were unmarkable except for small for gestational age. In Case 1, further umbilical blood puncture confirmed 22.4% and 34% trisomy 9 mosaicism by CMA and fluorescent in situ hybridization (FISH) respectively. After comprehensive consideration of the genetic and ultrasound results, the two gravidas decided to receive elective termination and molecular investigations of multiple tissue samples from the aborted fetus and the placenta. The results confirmed the presence of true fetoplacental mosaicism with levels of trisomy 9 mosaicism from 76% to normal in various tissues. These two cases highlight the necessity of genetic counseling for gravidas whose NIPT results highly suggest the risk of chromosome 9 to ascertain the occurrence of mosaicism. In addition, the comprehensive use of multiple genetic techniques and biological samples is recommended for prenatal diagnosis to avoid false-negative results. It should also be noted that ultrasound results of organs with true trisomy 9 mosaicism can be free of structural abnormalities during pregnancy.
摘要：
染色体镶嵌仍然是一个永久的诊断和临床难题。在本研究中,我们使用多种基因检测方法检测了2例产前9三体马赛克综合征病例。非侵入性产前检测（NIPT）结果表明，两个胎儿中的三体9。羊膜细胞的核型分析显示高水平（42％-50％）的镶嵌性，未培养羊膜细胞的染色体微阵列分析（CMA）显示，除了杂合性的大片段丢失外，没有拷贝数变异（CNV）。超声检查结果是无法标记的，除了小于胎龄。在病例1中，进一步的脐血穿刺通过CMA和荧光原位杂交（FISH）分别证实了22.4％和34％的9三体镶嵌性。在综合考虑遗传和超声结果后，两名孕妇决定接受来自流产胎儿和胎盘的多个组织样本的选择性终止和分子检查。结果证实了真正的胎儿胎盘镶嵌的存在，在各种组织中，三体9镶嵌的水平从76％变为正常。这两个案例突显了对孕妇进行遗传咨询的必要性，其NIPT结果高度表明9号染色体的风险，以确定镶嵌性的发生。此外,建议在产前诊断中综合使用多种遗传技术和生物样本,以避免假阴性结果.还应该注意的是，具有真正的三体性9镶嵌性的器官的超声结果在怀孕期间可以没有结构异常。
