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NIPT Test

Non-Invasive prenatal testing (also known as NIPT) is a test in which the blood sample of the pregnant woman is collected & the cell free DNA of the fetus which circulates in the pregnant mother’s blood is analyzed. This is a pre-natal screening test which helps in identifying the fetal chromosomal abnormalities like Down Syndrome (Trisomy 21), Edwards Syndrome (Trisomy 18) and Patau Syndrome (Trisomy 13). This test is also used to identify the gender (X & Y chromosome) upon request from the patient.

Background

DNA from the fetus can be found circulating in the mother’s blood. The fetal cells are naturally broken down, resulting in the fetal DNA circulating freely in the mother’s blood. This cell-free DNA (cfDNA) can be analyzed to estimate the risk of the fetus having trisomies 21, 18 or 13.

Indication

Although NIPT screening can be performed in every pregnancy, it is especially indicated:

• Pregnant women of age > 35yrs.
• Increased risk with first trimester screening.
• Affected previous child ,that is, Previous history or family history of Trisomy 13, 18 or 21
• Abnormal screening test for Trisomy 13, 18 or 21
• Abnormal ultrasound markers (level II ultrasound) suggestive of Trisomy 13, 18 or 21


Benefits

Since it is non-invasive there are no risks to the fetus as with invasive procedures (amniocentesis, CVS). NIPT test is highly sensitive and specific when compared to existing screening approaches for Down Syndrome. It detects around 99% of all babies with Down, Edwards and Patau syndromes.

Material
Blood sample from the mother (1 x 10 ml whole blood in special tube).
Method
Targeted sequencing of cell-free fetal DNA in maternal blood.


Results

A ‘HIGH RISK’ result indicates a high risk for a trisomy. Following up with invasive procedures is recommended in this case. The test identifies more than 99% of fetuses with trisomy 21, 98% of fetuses with trisomy 18, and 94% of fetuses with trisomy 13. The test is highly specific for Trisomy 21 (99.9%), 18 (99%) and 13 (99.9%).

X/Y analysis for singleton pregnancies

Extra, or incomplete copies of one of the sex chromosomes can be detected (XXX, XYY, XXYY, XXY and a missing X chromosome in a girl).

*X/Y analysis for twin pregnancies

Women who are pregnant with twins may complete NIPT at 12 weeks of pregnancy, however the gender of the babies cannot be accurately determined. Only the absence or presence of the Y chromosome can be detected.

Requirements

For singleton and twin pregnancies, live fetus,10 weeks of pregnancy by ultrasound, no vanishing twin.

Turnaround time

7-10 days

Please note

Patient must be 10weeks pregnant (gestation week 10) or later.

References:

1. Global perspectives on clinical adoption of NIPT
2. Accuracy of non-invasive prenatal testing using cell-free DNA for detection of Down, Edwards and Patau syndromes
3. DNA sequencing of maternal plasma reliably identifies trisomy 18 and trisomy 13 as well as Down syndrome
4. Performance of the neoBona test: a new paired-end massively parallel shotgun sequencing approach for cell-free DNA-based aneuploidy screening

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