Rapid Detection of Aneuploidies in Spontaneous Aborted Fetal Samples by Quantitative Fluorescence-PCR: A Descriptive Study

Chromosomal aneuploidies are the most chromosomal abnormalities at birth due to maternal meiosis I errors. Pregnancies with autosomal chromosomal aneuploidies that survive are namely trisomies 13 (Patau syndrome), 18 (Edward syndrome), and 21 (Down syndrome), account for 89% of chromosome abnormalities. Quantitative fluorescent polymerase chain reaction (QF-PCR) which amplifies specific DNA sequences called short tandem repeats (STRs), by using fluorescently labeled primers is a rapid technique for prenatal diagnosis of common aneuploidies. In this study, DNA extraction was performed from 100 samples isolated from muscle tissue of aborted fetuses. The analysis was performed by multiplex QF-PCR using a panel of 25 STRs markers for chromosomes X, Y, 13, 18, and 21. Our results showed that 20% of abortions were due to aneuploidy. 53% of mothers who had abortions were aged 26-35 years old and 32% of them were aged 36-45 years old. The analysis of muscle samples of aborted fetuses indicated that 20 samples showed chromosomal aneuploidy. Of the abnormal cases, 10 cases (~50 %) showed trisomy 21 followed by trisomy 18 (7 cases, ~35%), Klinefelter syndrome (2 cases, ~10 %), and showed trisomy X (1 case, ~5 %). Our results indicated that the D21S1414 marker showed the highest rate of heterozygosity in the study population. Besides some limitations of this study such as sample size, these results suggest that one of the causes of these abortions could be maternal age. We concluded that QF-PCR could be a rapid and reliable method to screen prenatal chromosomal aneuploidy and allow appropriate counseling.