Dr. Gauri Agarwal, Founder & Director, Seeds of Innocence and Genestrings Diagnostics
World Down Syndrome Day is observed every year on March 21 to raise awareness about this hereditary illness. Down Syndrome, also known as Trisomy 21, is a disorder in which an additional chromosome causes delays in a child’s mental and physical development. It is one of the most prevalent inherited birth diseases, affecting around 1 in every 830 live births. Every year, approximately 1.3 lakh children in India are born with this condition. Despite the worrying statistics, there is very little open discussion on this problem in India.
Prenatal genetic testing can eliminate the risk of Down Syndrome in babies
Down Syndrome can now be discovered in the early stages of pregnancy thanks to advances in medical science. Women who are at a higher risk of having a baby with Down syndrome can be identified through screening tests. These tests carry no risk of miscarriage and detect the likelihood of a baby being born with disorders such as Down Syndrome.
Why is genetic testing important?
Genetic testing is one of the most effective ways to not only predict a child’s future health, but also to understand the causes of infertility, miscarriages, and the overall incidences of congenital disorders. Prenatal testing reduces the burden of genetic illnesses and congenital impairments that cause considerable functional impairment after birth. Women who have undergone several abortions can use genetic screening to monitor their baby’s development on a regular basis.
Screening before marriage or before conception
Such screenings before marriage or conception help the couple to know whether their child will be at risk of any inherited or genetic ailment or not. It can be used to forecast the chance of an illness in an unborn infant, particularly if the ailment has a family history. In some circumstances, screening is also a preventative measure.
Carrier Screening for Genetic Conditions
Carrier screening is a term used to describe genetic testing that is performed on an individual who does not have any overt phenotype for a genetic disorder but may have one variant allele within a gene(s) associated with a diagnosis. Information about carrier screening should be provided to every pregnant woman. Carrier screening and counseling ideally should be performed before pregnancy because this enables couples to learn about their reproductive risk and consider the most complete range of reproductive options. If an individual is found to be a carrier for a specific condition, the patient’s reproductive partner should be offered testing in order to receive informed genetic counseling about potential reproductive outcomes. If both partners are found to be carriers of a genetic condition, genetic counseling should be offered. e.g., Thalassemia.
It is done when a genetic condition has already been diagnosed or if there’s a family history of it. It can detect diseases caused by mutations or nucleotides in genes. Mutation screening becomes a variable option for
It is widely accepted that about 85% of known disease-causing variants occur within 1% of the genome containing the exons and splice junctions; thus, surveying just this portion of the genome is an efficient and powerful clinical diagnostic tool for individual patients. By surveying virtually all protein-coding regions in the genome with this single test we not only replace the potential need for multiple costly single-gene sequencing tests but also drastically improve the odds of identifying a high-risk variant, which can then be used to guide appropriate clinical management. On average, 20,000 DNA variants are detected in exons per patient.
This test is intended for use in conjunction with the clinical presentation and other markers of disease progression for the management of patients with rare genetic disorders.
Screening after Conception
Non-Invasive Prenatal Test
This screening looks for a variety of irregularities in the genetic information stored in the DNA. The test is extremely sensitive to chromosomes 13,18 and 21 Trisomy’s. Expectant parents can rest assured that their child will be born free from hereditary problems thanks to this wonderful technology.
In this technique, amniotic fluid (a fluid that surrounds and protects a foetus during pregnancy) is removed from the uterus for testing. It helps to identify the problems in the foetus. Amniotic fluid is the fluid that surrounds and protects a baby during pregnancy. This fluid contains fetal cells and various proteins. Chromosomal microarray analysis (CMA) is a technology used for the detection of clinically-significant microdeletions or duplications, with high sensitivity for sub-microscopic aberrations. It is having an increasingly important role in prenatal testing and may be used as a primary screening tool.
Who should go for genetic screening?
The likelihood of having a Down syndrome baby is often proportional to the mother’s age. The chances of having a kid with Down syndrome are roughly 1 in 1,400 if you are under the age of 25. At 35, your chances are roughly 1 in 350. At the age of 40, the chances are about one in a hundred. Genetic testing can reveal changes (mutations) in your genes that may cause illness or disease.
1. Hereditary testing may be recommended for those who are at a higher risk of having a child with a genetic condition. This includes families with genetic illnesses in close relatives, parents who already have a child with a genetic illness, couples planning to start a family and one of them or a close relative has a genetic illness, pregnant women over 34 or who have had two or more miscarriages, or women who have delivered a stillborn baby with physical signs of a genetic disorder.
Pregnancies with a higher risk of chromosome abnormalities in the foetus should be genetically tested on all pregnant women between the ages of 22 and 50, regardless of risk. Indications for genetic testing are as below-
• Confirmation of the diagnosis of a medical condition that is genetic in nature, for a child or an adult
• If there is a family history of a specific disease
• If several members of a family present with symptoms of the same disease
• If there is concern over passing a genetic disease to the next generation
• If the couple are blood relatives and have entered into a consanguineous marriage
• If a couple wants to start a family and one of them has a family history of a disease, genetic testing will reveal if they are “carriers” of a particular illness
• If a woman is pregnant and are above the age of 30
• If a woman has had more than two spontaneous abortions
• If a woman’s baby was stillborn and the baby’s physical characteristics indicated a genetic disease
• If a couple already has had a child with a genetic disease and is planning for the next child
Pregnancies with a higher risk of chromosome abnormalities in the foetus should be genetically tested on all pregnant women between the ages of 22 and 50, regardless of risk. Fertility clinics with their own in-house lab facility lower the danger of sample mishandling by eliminating logistics and increasing the likelihood of efficacy and accuracy by using cutting-edge technology. Labs that offer such tests should offer speedy response times at reasonable prices, as well as proper post-diagnosis consultation by competent doctors.