QF-PCR test in prenatal diagnosis

The article was professionally consulted by Doctor Head of Obstetrics and Gynecology Department - Department of Obstetrics and Gynecology - Vinmec Hai Phong International General Hospital.

Fetal malformations are defects in the body that a baby has while in the womb, sometimes it takes until birth to recognize it. Today, thanks to the development of medicine, parents can detect fetal malformations in the womb thanks to prenatal diagnostic tests, including QF-PCR test.

QF-PCR (quantitative fluorescence PCR) is a test that uses molecular biology techniques to diagnose certain aneuploidy (chromosomal) abnormalities of the fetus from amniotic cells.
The test uses gene fragmentation (PCR) to amplify short fetal-specific DNA fragments. The amplified DNA fragments were labeled with fluorescent signals and quantified by capillary electrophoresis on the ABI 3500 gene sequencing system.

An aneuploidy of chromosome number 21 also known as trisomy 21 causes Down syndrome. An aneuploidy of chromosome 13, also known as trisomy 13, causes Patau syndrome. An aneuploidy of 18, also known as trisomy 18, causes Edwards syndrome. X, Y sex chromosome aberrations are seen in syndromes such as Turner, Klinefelter, Jacobs... Currently, QF-PCR is often indicated in rapid prenatal diagnosis of chromosomal disorders for high-risk pregnancies. Down Syndrome, Edwards Syndrome, Turner Syndrome, Klinefelter Syndrome...

The test is usually ordered in conjunction with the amniocentesis and is indicated when the pregnant woman has at least one of the following factors:
Maternal serum screening test (eg: Double test , Triple test ) has a high risk of having a baby with a birth defect. Fetal ultrasound shows abnormal images: Back clearance ≥ 3mm, nasal bone hypoplasia, fists, crooked feet, some malformations such as heart defects, digestive tract defects... Pregnant women over 35 year old. History of pregnancy or birth of a child with a genetic disease. Pregnant women and/or husbands with chromosomal abnormalities or family history of genetic diseases.

Blood. Amniotic fluid. Vegetable spines. Umbilical cord, cord blood.

Advantages: QF-PCR test is 100% accurate in detecting common aneuploidies: Down syndrome, Edward, Patau, Turner, Klinefelter. No need for incubation time, so the results are returned within 2-3 days. Only a small amount of amniotic cells are needed. Limitations: Only aneuploidy of 5 chromosomes can be evaluated, but not all 46 chromosomes in the set of chromosomes. Some structural abnormalities were not detected: inversions, balanced translocations and mosaicism... Can't detect chromosomal deletions with small size < 2Mb.