QFPCR

Quantitative Fluorescence PCR (QF-PCR) is a molecular-based technique employed for prenatal and postnatal diagnosis of rapid aneuploidy detection(RAD) of chromosomes 13, 18, 21, X, and Y.
A technique based on the amplification of chromosome-specific DNA sequences (STR, short tandem repeats) polymorphic in length, is used to determine the presence of different alleles. Employing fluorescent primers, the amplified segments can be visualized and quantified as peak areas on automated DNA scanners.
QF-PCR is rapid, cost-effective, almost entirely automated, small sample size with high accuracy, and can detect most abnormalities diagnosed by conventional karyotyping.

Prenatal

QF-PCR is offered prenatally if one or more of these indications are present

Postnatal

QF-PCR can detect

Requires a small sample and allows automation of the procedure, providing a rapid turnaround time at a lower cost than conventional cytogenetics. Moreover, diagnostic testing with QF-PCR eliminates the unexpected or incidental identification of rare chromosomal abnormalities of uncertain significance

Genomic DNA for QF-PCR is extracted using-

The principle behind QF-PCR is Specific DNA Markers (Short Tandem Repeats or STRs) that bind across the regions of chromosomes

3-5 STR binds across chromosomes 13,18,21 and sex chromosomes which are amplified by PCR.
Primers used to amplify each section of DNA are labeled with different colored fluorescent tags and the amplification products are different sizes.

The amount of fluorescence and size of the DNA which has been copied is measured, and ratios are presented graphically which allows

A distinction of the chromosomal regions.
The number of peaks and height of each peak shows the number of copies of alleles at that region on the chromosome in the DNA sample.

QF-PCR cannot detect any changes that lie outside the target sequence of the markers and will not detect balanced rearrangements.
QF-PCR is not designed to detect trisomies other than 13, 18, and 21 and will not detect most unbalanced chromosomal abnormalities, nor will it detect balanced rearrangements. Therefore, a patient with a negative QF-PCR result has a residual risk of having a pregnancy with a chromosomal abnormality detectable on conventional chromosome analysis.
Both conventional cytogenetics and QF-PCR should be performed in all cases of prenatal diagnosis referred for a fetal ultrasound abnormality.
Low frequency of severe abnormalities not detected by QF-PCR but revealed by conventional karyotyping.

Overview	Indications	Application	Reporting/Features
Sample Requirement	Methodology	Limitations