Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road, NUHS Tower Block, Level 12, Singapore 119228, Singapore.
iGene Laboratory Pte Ltd., 1 Science Park Road #04-10, The Capricorn, Singapore 117528, Singapore.
Genes (Basel). 2022 Nov 30;13(12):2257. doi: 10.3390/genes13122257.
The current gold standard for the definitive diagnosis of fetal aneuploidy uses either chorionic villus sampling (CVS) or amniocentesis, both of which are which are invasive procedures carrying a procedure-related risk of miscarriage of up to 0.1-0.2%. Non-invasive prenatal diagnosis using fetal nucleated red blood cells (FNRBCs) isolated from maternal peripheral venous blood would remove this risk of miscarriage since these cells can be isolated from the mother's blood. We aimed to detect whole-chromosome aneuploidies from single nucleated fetal red blood cells using whole-genome amplification followed by massively parallel sequencing performed on a semiconductor sequencing platform. Twenty-six single cells were picked from the placental villi of twelve patients thought to have a normal fetal genotype and who were undergoing elective first-trimester surgical termination of pregnancy. Following karyotyping, it was subsequently found that two of these cases were also abnormal (one trisomy 15 and one mosaic genotype). One single cell from chorionic villus samples for two patients carrying a fetus with trisomy 21 and two single cells from women carrying fetuses with T18 were also picked. Pooled libraries were sequenced on the Ion Proton and data were analysed using Ion Reporter software. We correctly classified fetal genotype in all 24 normal cells, as well as the 2 T21 cells, the 2 T18 cells, and the two T15 cells. The two cells picked from the fetus with a mosaic result by CVS were classified as unaffected, suggesting that this was a case of confined placental mosaicism. Fetal sex was correctly assigned in all cases. We demonstrated that semiconductor sequencing using commercially available software for data analysis can be achieved for the non-invasive prenatal diagnosis of whole-chromosome aneuploidy with 100% accuracy.
目前，诊断胎儿非整倍体的金标准是使用绒毛膜绒毛取样（CVS）或羊膜穿刺术，这两种方法都是有创的，与手术相关的流产风险高达 0.1-0.2%。使用从母亲外周静脉血中分离的胎儿有核红细胞（FNRBC）进行非侵入性产前诊断，可以消除这种流产风险，因为这些细胞可以从母亲的血液中分离出来。我们旨在通过全基因组扩增检测来自单个有核胎儿红细胞的全染色体非整倍体，然后在半导体测序平台上进行大规模平行测序。从 12 名被认为胎儿基因型正常且正在进行选择性妊娠早期手术终止妊娠的患者的胎盘绒毛中挑选了 26 个单个细胞。进行核型分析后，发现其中两个病例也异常（一个三体 15，一个嵌合体基因型）。从携带三体 21 胎儿的两名患者的绒毛取样中也挑选了一个单个细胞，以及从携带 T18 胎儿的两名患者的两个单个细胞。将混合文库在 Ion Proton 上进行测序，并使用 Ion Reporter 软件对数据进行分析。我们正确地对所有 24 个正常细胞、2 个 T21 细胞、2 个 T18 细胞和 2 个 T15 细胞的胎儿基因型进行了分类。从 CVS 获得的嵌合体结果的胎儿中挑选的两个细胞被归类为未受影响的细胞，这表明这是一个局限于胎盘嵌合体的病例。在所有情况下，胎儿性别均正确分配。我们证明，使用商业上可用于数据分析的半导体测序，可以实现全染色体非整倍体的非侵入性产前诊断，准确率为 100%。
