Rapid QF-PCR Testing

There may be a more appropriate test, please see: Prenatal – Abnormal Ultrasound Scan Findings

Introduction

Quantitative-Fluorescent PCR (QF-PCR) is a rapid molecular test for the identification of common aneuploidy syndromes, specifically chromosomes 13, 18 and 21 and the sex chromosomes.

Referral information

QF-PCR testing is carried out for aneuploidies 13, 18 and 21 on all chorionic villus and amniotic fluid samples unless the sample is too small, unsuitable, or the test is specifically not requested. Sex chromosome aneuploidy is carried out on chorionic villus and amniotic fluid samples if cystic hygroma or raised nuchal translucency is detected on ultrasound scan.  Samples that do not meet the criteria for microarray analysis are tested by QF-PCR only. Samples that meet the requirements for microarray analysis should be accompanied by a maternal blood sample in EDTA to exclude maternal cell contamination.

QF-PCR is performed on fetal tissue samples for confirmation of a prenatal result and as the first tier test for pregnancy loss samples that fall within our Acceptance Criteria.

QF-PCR testing is also performed on blood samples from new-born babies where an aneuploidy is suspected (trisomy 13, 18 or 21) or for those with ambiguous genitalia (sex chromosome testing).

Price & reporting times

NHS referrals to this service are paid for where there is an existing specialist commissioning contract for genetic testing. In other cases please contact the lab for prices. For same day processing, prenatal samples must arrive at the laboratory before 1pm. We aim to report all prenatal and urgent postnatal samples within 3 calendar days.  Routine postnatal samples are reported within 28 days.

Test Price (£ ex VAT) TRT *
Prenatal amniotic fluid or chorionic villus sample POA 3 cd
Urgent postnatal blood sample POA 3 cd
Routine postnatal sample POA 28 cd

Test validation & quality assurance - information for users

QF-PCR may not detect mosaicism or structural rearrangements. Rarely, testing may be uninformative or fail to give a result either due to maternal cell contamination or other factors. Maternal and paternal blood samples may be requested to help interpret results. Maternal cell contamination is excluded for prenatal samples prior to microarray testing by analysis of a maternal blood sample. This laboratory participates in the CEQAS quality assessment scheme for this test.

Short tandem repeat microsatellite markers used for QF-PCR testing are as follows:

Chromosome 13 – D13S742 (13q12), D13S305 (13q13), D13S634 (13q21.3), D13S628 (13q31).

Chromosome 18 – D18S391 (18p11.2), D18S535 (18q12), D18S978 (18q12.3), D18S386 (18q22).

Chromosome 21 – D21S1270 (21q21), D21S11 (21q21.1), D21S1435 (21q21.2), D21S1411 (21q22.3).

X chromosome – DXS1283E(Xp22.3), DXS996(Xp22.3), DXS981(Xq11.2-q13.1), TAF9B (Xq21.1), XHPRT(Xq26.1), DXS6854(Xq26), P39(Xq28).

Y chromosome – DYS448 (Yq11.2), SRY (Yp11.3).

X and Y chromosomes – X22 (Xq28, Yq12), AMXY (Xp22.2, Yp11.2)

Sample requirements

5ml Lithium Heparin blood sample (1-2ml volume sufficient for younger/difficult to bleed patients) and 4ml EDTA blood sample if possible.

Referral guidelines

Please see our referral guidelines for more information.

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