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NIPT (Non-invasive Prenatal Testing)

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NIPT (Non-invasive Prenatal Testing)

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Gene vs. Chromosome

In a nutshell, a gene is a segment of DNA, and 1 DNA molecule makes 1 chromosome. A chromosome is a large structure made of many smaller segments called genes.

All humans have a fixed number of chromosomes i.e. 23 pairs (total 46 chromosomes). Of these, 01 pair identifies gender and are known as the sex chromosomes, which are usually XX for female and XY for male. The remaining 22 pairs (autosomes) contain instructions for the structure and function of each and every part of the body. The instructions are encoded in DNA, which is a very long molecule that is twisted and coiled into the shape of a chromosome. Our height, eye colour, risk of disease, and inheritance of certain conditions (e.g. thalassemia) are just a few examples of the functions of our DNA. Each part of DNA has a specific code for a specific function – this is called a gene.

1 chromosome in each pair is inherited from the mother and the other from the father.

What is NIPT?

NIPT stands for Non-invasive prenatal testing. It is a type of genetic test that evaluates the baby’s DNA by extracting it from the mother’s blood. Fetal DNA (known as cell-free fetal DNA or cffDNA) is DNA of the baby that passes the placenta and is present in the mother’s blood. This phenomenon only occurs during pregnancy; as soon as the baby is delivered, its DNA is cleared from maternal blood within a few hours.

NIPT is also a screening test, which means that it is a rapid test that identifies those fetuses that have a high probability (or risk) of certain genetic diseases. It is not intended to be a diagnostic test. If NIPT identifies a high risk of a disease, further testing will be required to confirm this.

Gene vs. Chromosome

In a nutshell, a gene is a segment of DNA, and 1 DNA molecule makes 1 chromosome. A chromosome is a large structure made of many smaller segments called genes.

All humans have a fixed number of chromosomes i.e. 23 pairs (total 46 chromosomes). Of these, 01 pair identifies gender and are known as the sex chromosomes, which are usually XX for female and XY for male. The remaining 22 pairs (autosomes) contain instructions for the structure and function of each and every part of the body. The instructions are encoded in DNA, which is a very long molecule that is twisted and coiled into the shape of a chromosome. Our height, eye colour, risk of disease, and inheritance of certain conditions (e.g. thalassemia) are just a few examples of the functions of our DNA. Each part of DNA has a specific code for a specific function – this is called a gene.

1 chromosome in each pair is inherited from the mother and the other from the father.

What is NIPT?

NIPT stands for Non-invasive prenatal testing. It is a type of genetic test that evaluates the baby’s DNA by extracting it from the mother’s blood. Fetal DNA (known as cell-free fetal DNA or cffDNA) is DNA of the baby that passes the placenta and is present in the mother’s blood. This phenomenon only occurs during pregnancy; as soon as the baby is delivered, its DNA is cleared from maternal blood within a few hours.

NIPT is also a screening test, which means that it is a rapid test that identifies those fetuses that have a high probability (or risk) of certain genetic diseases. It is not intended to be a diagnostic test. If NIPT identifies a high risk of a disease, further testing will be required to confirm this.

NIPT essentially looks at the number and shape of the baby’s chromosomes and compares it to normal chromosome number and size. It does NOT look at the genes inside the chromosome.

NIPT is able to see if the baby has a normal number of chromosomes (i.e. 46 in total) and if any chromosomes are absent or extra in number. 

For example, if there is an extra chromosome 21, this would be called trisomy 21 (‘tri’ meaning ‘three’) and would lead to a condition called Down Syndrome. If one of the sex chromosomes is missing, this would be called monosomy X (‘mono’ meaning ‘single’) and would lead to the condition called Turner Syndrome. 

Not all conditions of extra or missing chromosomes lead to fatal disease. Children with Down Syndrome or Turner Syndrome can lead very normal lives, with an increased risk of certain problems such as heart disease.

It can also identify if large segments of a chromosome are missing or duplicated – these can lead to diseases of varying severity.

There are three main types – all work the same way

  1. NIPT 5 – this looks at 5 chromosomes only – chromosome number 13, 18, 21, and the sex chromosomes. This is the most commonly performed NIPT test because diseases of these chromosomes are far more commoner than those of other chromosomes. It also has a lower cost than the other NIPT tests.
  2. NIPT 24 – this looks at the number of all 24 pairs of chromosomes
  3. NIPT 24 extended – this not only looks at the number of chromosomes but also tries to identify large breaks or duplications or segments of the chromosome.

NOTE: as NIPT is only a screening test and not diagnostic, any anomaly identified would have to be confirmed by other means of testing.

Not all pregnancies require NIPT testing, although in some countries it is offered to all women who are pregnant. Your doctor will recommend NIPT if

  • There is a suspicion of abnormality in the baby on ultrasound, especially an increase in a measurement called NT (nuchal translucency) – this is normally tested in the 11-14 week ultrasound scan (dating scan) and is a must for all pregnancies.
  • You have had an abnormal baby previously
  • You have a family history of abnormal babies
  • Your age is 35 years or more at the time of conceiving

However, if you do not fall into any of the above categories and still want more information about your baby, you can get the test done at Medicsi.

Yes, you can find out about your baby’s gender through NIPT, as well as any major structural problems in the chromosomes that define gender.

Gender is only revealed if you consent to this. At the time of testing, you will be specifically asked this; if you do not want to know the gender you can decline and the gender will not be revealed in the report.

You can get NIPT done as early as 10 weeks. The exact age of the pregnancy needs to be confirmed by an ultrasound scan and cannot be estimated by the date of the last menstrual period.

  • The age of the pregnancy must be confirmed through ultrasound and must be greater than 10 weeks
  • Only singleton and twin pregnancies can be tested. Triplet pregnancies cannot undergo NIPT 
  • Certain medical conditions and therapies must be ruled out, which will be discussed during your NIPT consultation

A ‘normal’ result means that your baby is a LOW RISK for chromosomal disease. Although NIPT is very accurate, there is a small possibility of a ‘false normal’ report (also known as a false negative).

A low-risk NIPT result does not mean that the baby cannot develop abnormalities of different kinds later in pregnancy. Many abnormalities are not detected until late pregnancy or even after the baby is born; this may be because

  • Ultrasound CANNOT detect 100% abnormalities
  • Some diseases show abnormal features later in life

An abnormal NIPT result would mean that the test has identified your baby as HIGH RISK for chromosomal disease and would require further testing e.g. CVS or amniocentesis, to confirm this suspicion. Although NIPT is very accurate, there is a chance that the NIPT has mis-identified the abnormality (known as ‘false positive’).

Additionally, genes are not tested on NIPT and the possibility of simultaneous chromosome and gene disorder cannot be excluded.

NIPT has the following advantages over diagnostic testing.

  • It is non-invasive i.e. it only requires the mother’s blood and carries no risk to the baby. Invasive testing (CVS or amniocentesis) has a small risk to the baby
  • It can be performed earlier in pregnancy than invasive testing
  • It is quicker for the patient as it only requires a blood sample

In modern medicine, non-invasive testing has largely replaced invasive tests and is considered first-line in the investigation of disease.

It is now possible for certain diseases caused by genes to be detected by NIPT as well; however, this technology is newer and less validated than traditional NIPT for chromosomes. If you have a disease that runs in your family, please discuss this with your primary Consultant at Medicsi, who will arrange the appropriate service to best address the problem.

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About Us

Medicsi, established in 2006, prioritizes cutting-edge diagnostic technology in the treatment decisions of our patients. Our institution emphasizes patient comfort and employs competent senior consultants to oversee their care.

Newsletters

Recent Blogs

  • All Post
  • Baby Health Matters
  • Healthy Life Tips
  • Physician Notes
  • Pregnancy
  • Subfertility​
  • Surgical Expertise
    •   Back
    • Labour

Our Locations

Our Locations

Bahria Town (Lab)

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