背景:母体血浆中所谓的无细胞胎儿DNA(cffDNA),它来自胎盘,广泛用于筛选胎儿非整倍体,包括21、18、13三体性染色体。在这里,我们报道了一例8三体镶嵌症(T8M),最初是通过非侵入性产前检测(NIPT)中的cffDNA筛查鉴定的。
方法:一名35岁女性在妊娠第17周时接受了cffDNA筛查。随后进行了羊膜穿刺术,和核型分析,使用单核苷酸多态性阵列(SNP-array)和BACs-on-Beads™(BoBs™)测定胎儿染色体含量.应用间期荧光原位杂交(FISH)测定8号染色体的拷贝数。
结果:通过cffDNA筛查,在研究的孕妇中发现胎儿8三体的风险增加。羊膜穿刺术后,在73个中期中有1个发现了三体性8。来自培养的羊膜细胞和新生儿脐带血细胞的DNA上的SNP阵列表明存在T8M。天然新生儿脐带血细胞的间期FISH以10%的百分比证实T8M。Bobs™荧光数据还表明8q23-8q24被扩增。
结论:目前的研究表明,NIPT适合提供关于罕见常染色体三体的提示,这必须通过其他方法进一步验证和确认。
BACKGROUND: So called cell-free fetal DNA (cffDNA) in the maternal plasma, which is derived from placenta, is widely used to screen fetal aneuploidies, including trisomy 21, 18, 13 and sex chromosomes. Here we reported a case of trisomy 8 mosaicism (T8M), which was initially identified via cffDNA screening in noninvasive prenatal testing (NIPT).
METHODS: A 35-year-old woman received cffDNA screening at 17th week of gestation. Amniocentesis was performed subsequently, and karyotyping, single-nucleotide polymorphism array (SNP-array) and BACs-on-Beads™ (BoBs™) were used to determine fetal chromosome content. Interphase fluorescence in situ hybridization (FISH) was applied to determine the copy number of chromosome 8.
RESULTS: An enhanced risk for fetal trisomy 8 was identified by cffDNA screening in the studied pregnant woman. After amniocentesis trisomy 8 was found in 1 of 73 metaphases. SNP-array on DNA derived from cultured amniocytes and neonatal cord blood cells suggested the presence of T8M. Interphase FISH on native neonatal cord blood cells confirmed T8M with a percentage of 10%. The Bobs™ fluorescence data also suggested that 8q23-8q24 was amplified.
CONCLUSIONS: The current study shows that NIPT is suited to provide hints on rare autosomal trisomies, which have to be further validated and confirmed by other approaches.