Non-invasive prenatal testing (NIPT) describes a very exciting new set of technologies that enable a simple maternal blood test to identify whether a fetus has any genetic abnormality or not. It has marked a revolution in aneuploidy and genetic screenings because it is safe and provides high level of reassurance for the presence of any genetic disorder in fetus early in pregnancy. Pregnant women, who have greater chances of high risk pregnancy due to family history of congenital abnormalities or are in their advanced maternal age, can opt for NIPT test from 10 weeks of gestation period. This test has been validated in a high-risk population and can be used for screening:
Due to the detection of fetal DNA in maternal blood, NIPT of fetal aneuploidy is becoming more promising. NIPT can screen for aneuploidy such as Down Syndrome (Trisomy 21), Edwards Syndrome, Turner Syndrome and Patau Syndrome. NIPT analyses both maternal and fetal DNA and look for differences in the DNA methylation patterns to detect aneuploidy in fetus.
Single gene disorders
Some single gene disorders are inherited in a dominant fashion from the father to fetus or arise de novo. In these situations, pregnant women, at high risk of having fetus with single gene disorders, can opt for NIPT. cffDNA of fetus with single gene disorders contain altered alleles that are not present in the maternal cfDNA. NIPT is available for achondroplasia, thanatophoric dysplasia and Apert syndrome.
Fetal blood genotyping
It is possible to analyse cffDNA of fetus for detecting the presence of Kell antibodies and human platelet antibodies (HPA). NIPT can also be used to analyse other genes in order to predict blood antibody status of fetus.
By using advanced bioinformatics algorithms after maternal blood testing, NIPT can detect the presence of microdeletion syndrome in fetus such as Cri-du-Chat, Prader Willi and Angelman.
Rhesus D (RhD) typing in RhD- mothers
When the pregnant woman is RhD- and the fetus has inherited the RhD+ gene from father, then there are chances of developing haemolytic disease by the fetus. This condition is called haemolytic disease of the newborn (HDN). NIPT can be used to detect such condition, using which couples can take necessary prenatal care and optimum management.
When a pregnant woman is suffering from Duchenne muscular dystrophy or congenital adrenal hyperplasia (CAH) or both father and mother carry altered genes of CAH, then chances of the fetus carrying altered X gene increases. In such cases, NIPT can be used for fetal sex determination, so as to determine whether male fetus has inherited the condition from the mother or not.
In comparison to invasive screening options, non-invasive prenatal testing provides more reliable results with a higher positive predictive result. NIPT offers tremendous potential as a screening tool for fetal aneuploidy, gene disorders or other chromosomal abnormalities. NIPT is poised to significantly shift the paradigm of Diagnosi Prenatale in coming years because of its high reliability and accuracy and low risk.