Refined fluorescent STR quantification of cell-free fetal DNA during pregnancy in physiological and Down syndrome fetuses.
BACKGROUND
Cell-free fetal (cff) DNA analysis by short tandem repeats (STR) has the advantage of better recognizing the different genotypes. However, quantitative examination by quantitative fluorescent (QF) polymerase chain reaction (PCR) by STRs is limited to only a rough approximation. This project focuses on a more precise calculation of the relative cff DNA amount tested in the STRs' loci.


METHODS
The cff DNA was analyzed in 363 samples from 258 pregnant women with physiological fetuses in different stages of pregnancy (from 4-37 gestational weeks) separately in three STRs [D21S1435, D21S1446 and PentaD (pD)] and also by gonosomal sequences amelogenin gene, X/Y-linked/testis specific protein, Y-linked (AMELX/Y/TSPY). Seventeen samples of cff DNA from fetuses with Down syndrome (DS) were compared. We optimized the refined quantitative fluorescent (RQF) PCR for STRs in a particular locus.


CONCLUSIONS
The cff DNA detection rate was 74% in at least one of the STRs. The efficiency decreased from shorter to longer PCR fragments. All three STR and gonosomal loci proved an increase in cff DNA during pregnancy. The stutter variability rate is greatest in short STR fragments and decreases as the STR fragments increase in length. Results showed that DS samples had a significantly higher amount of cff DNA.
Vodicka
Radek
R
Department of Clinical Genetics and Fetal Medicine, University Hospital Olomouc, I.P Pavlova 6, 775 20 Olomouc, Czech Republic.
Vrtel
Radek
R
Dusek
Ladislav
L
Prochazka
Martin
M
Schneiderova
Eva
E
Vrbicka
Dita
D
Krejcirikova
Eva
E
Dhaifalah
Ishraq
I
Santava
Alena
A
Santavy
Jiri
J
D004247:DNA / Q000097:blood*; D004314:Down Syndrome / Q000235:genetics*; D005260:Female; D005331:Fetomaternal Transfusion / Q000235:genetics*; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics*; D011247:Pregnancy; D011296:Prenatal Diagnosis
D004247:DNA