[Rapid detection of the most common chromosomal aneuploidies in the second-trimester amniotic fluid using QF-PCR].

OBJECTIVE

To introduce QF-PCR method for detection of the most common chromosomal (trisomy 21, 18 and 13) and gonosomal aneuploidies at our department in the second-trimester amniotic fluid. To test the hypothesis of chromosomal aneuploidies detection using STR markers of Aneufast® kit via analysing free fetal DNA (ffDNA) isolated from plasma of pregnant women with confirmed trisomy 21 in fetus.

DESIGN

A prospective clinical study.

SETTING

Department of Obstetrics and Gynecology, Jessenius Faculty of Medicine and University Hospital in Martin, Slovak Republic.

METHODS

The samples of amniotic fluid were obtained from 67 women (twin pregnancy in 3 cases) in the 2nd trimester (15th to 22nd gestational week (g.w.)). Samples were examined using multiplex QF-PCR via Aneufast kit. In the case of positivity for trisomy 21, they were re-examined using Devyser Resolution 21 kit. All samples were parallelly evaluated by cytogenetic karyotyping. We also analyzed ffDNA from the plasma of 3 high-risk women using Aneufast kit. The plasma samples were obtained in the 2nd trimester(17th to 21st g.w.). Qiaamp DSP Virus kit was used for ffDNA isolation. Trisomy 21 of 3 fetuses was confirmed by karyotyping after 2nd trimester amniocentesis.

RESULTS

In the cohort of 70 samples, 7 pathological results (six trisomies 21 and one trisomy 18) were obtained. There was 100% concordance with cytogenetic karyotype in all samples examined by QF-PCR. The amplification of tracked chromosome 21 fragments was not evaluable in the case of ffDNA analysis.

CONCLUSION

QF-PCR was approved as reliable, rapid, quite simple and financially bearable method of prenatal diagnostics. Despite the fact of good availability and work implementation of Aneufast® kit, results of ffDNA analysis are insufficient. We did not obtain interpretable results after ffDNA analysis from maternal plasma in trisomy 21 fetuses.