By Dr. Aparna Rajadhyaksha MD
Becoming a parent is an extraordinary experience. The magic starts when the family finds out they are expecting a child.
The worry about having a healthy child starts right around then. The first worry is if the fetus is growing well, and the pregnancy will culminate in healthy baby born without any abnormalities.
This risk of a genetic abnormality goes up as the age of the mother increases. For example, the risk of having a child with Down’s Syndrome caused by an extra copy of chromosome 21 that leads to developmental delay, heart disease and other abnormalities in the child is 1/1,300 for a 25-year-old woman; at age 35, the risk increases to 1/365. At age 45, the risk of a having a child with Down syndrome increases to 1/30.
Physicians have been aware of that for a long time. Women who get pregnant are usually screened for these types of abnormalities using blood tests and ultrasound. These do not give a definitive diagnosis. The only way to obtain one would be through invasive testing such as Chorionic Villus Sampling (CVS) and/or Amniocentesis. Whereby, cells of the fetus are sampled to look for chromosomal abnormalities.
Now, there are other modalities whereby, a patient can be screened for chromosomal abnormalities Noninvasive prenatal testing (NIPT), sometimes called noninvasive prenatal screening (NIPS), is a revolutionary method of determining the risk that the fetus will be born with certain chromosomal abnormalities without harming the fetus. This testing analyzes small fragments of DNA that are circulating in a pregnant woman’s blood around 10-12 weeks of pregnancy.
NIPT primarily looks for Down syndrome, Edward Syndrome (trisomy 18), Patau Syndrome (trisomy 13) and extra or missing copies of the X and Y chromosomes (the sex chromosomes). The accuracy of the test varies by disorder Down’s Syndrome being the most accurate at 99%.
NIPT is a screening test. If there is an increased risk detected on NIPT or on ultrasound studies, the patient is counseled and advised to go through CVS or amniocentesis to confirm this finding.
Once the cells from the fetus are sampled, they are cultured to grow to analyze the chromosomes for abnormalities. For some reason, if the cells are not sampled appropriately or do not grow there are other methodologies such as the chromosomal microarray. Here, cells do not need be cultured. In fact, the chromosomal microarray picks up the tiniest of abnormalities which regular chromosomal analysis may have missed providing a definitive diagnosis for the family in assist them in making the best possible decision for them on how to proceed with the pregnancy.
Welcoming a new baby into the world is life changing. Making sure the baby is healthy right from the time of pregnancy is a priority for expectant couples and a cause of much stress. Genetic testing has become so easy and streamlined hopefully allays a lot of those fears so that families can move on to the next step in their lives with anticipation and not fear.
(The author is Medical Consultant, Metropolis Healthcare Limited. Views expressed are personal and do not reflect the official position or policy of the FinancialExpress.com.)