Prenatal or Post-Conception Screening

WHAT IS NON-INVASIVE PRENATAL GENETIC TESTING (NIPT)?

As the name suggests, NIPT is a genetic testing procedure performed after conception in which an invasive procedure is not required for the detection of an abnormal number of chromosomes in the developing fetus. With increasing age at conception, the risk of having a baby with developmental and mental disability increases. In such cases, doctors perform an invasive procedure called genetic amniocentesis. In this procedure a needle is inserted through the abdomen of the pregnant woman into the uterus to collect amniotic fluid, which surrounds the baby. The amniotic fluid contains cells derived from the baby. These cells are then examined under the microscope to look for extra, missing, or structurally modified chromosomes. Though rare, risks, including miscarriage, infection, and injury to baby, are present. In any case, the procedure is very unpleasant. Recent advances in whole-genome sequencing allow this test to be performed on blood drawn from a pregnant mother rather than inserting the needle in the abdomen and uterus. Using a very specialized next generation DNA sequencing method, scientists can detect the DNA sequence of the fetus’s DNA in the mother’s blood. They then analyze the contribution made by different chromosomes and determine whether the sequence of a particular chromosome is more than expected … which could point to the baby being born with a chromosome copy number abnormality such as Down, Edwards, or Turner syndrome. Thus, by using the next generation sequencing of DNA isolated from the pregnant woman’s blood, the risky genetic amniocentesis procedure is avoided.