We all have genes. These genes contain not just DNA from our parents and ancestors but they also control how each and every part of the body looks and functions. Genes always come in pairs and are present in every cell of our body. Every cell contains 23 different pairs of chromosomes. When there are changes or defects in these genes or chromosomes, it results in genetic disorders.
With the advancement of science and technology, we can identify certain genetic disorders during the pregnancy itself and some genetic disorders go undetected until the baby is much older. These genetic disorders can be physical or intellectual problems.
The chromosomes carry the genes which give instructions for how the body should develop, function and appear. It is natural for these genes to undergo changes as they mix - genes from the father and genes from the mother mix to form genes for the baby. When they undergo harmful changes, it will affect the way the baby develops.
These harmful changes lead to disorders in the baby and the baby will carry the genetic disorder in its genes, which will pass on to the next generation. Genetic disorders can be hereditary or can happen for the first time in the baby. One or both parents could unknowingly carry some defective chromosome which can cause issues in the baby.
It is not always possible to be certain about a genetic disorder until you detect it in the baby’s blood. The following factors indicate the mother-to-be is at a higher risk of carrying a baby with a genetic disorder:
● History of genetic disorder in the family
● Already have a child with a genetic disorder
● One or both parents have chromosomal abnormalities
● Mother is above 35 years of age
● Father is above 45 years of age
● Multiple miscarriages in the past
● Had a stillbirth
● Exposure to harmful chemicals or drugs before or during pregnancy
The exact way in which a genetic disorder or an abnormal chromosome will affect the pregnancy or the baby cannot be determined. Some conditions may not cause any symptoms and some conditions that were silent in the mother may act up in the baby.
Some genetic disorders that can affect a foetus during pregnancy are:
● Single-Gene-Disorders occur when there is a change in just one gene and it causes some disease.
● Chromosomal Abnormalities occur when there are fewer or more number of chromosomes or if the chromosomes are in pieces.
● Multifactorial Disorders are caused by a combination of genetic disorders and environmental factors. This makes it difficult to identify who is at risk.
● Teratogenic Disorders occur when the baby is exposed to certain drugs or substances during pregnancy. So, the parents are not the carriers but the baby gets affected first.
Some genetic disorders are hereditary – meaning they are passed on from the parents to the baby. In case of a family history of such disorders or if one of the previously born babies has a disorder, it is important to undergo these tests during pregnancy. These tests can help identify similar disorders in the foetus and take necessary action at the earliest:
These tests screen the foetus for certain genetic disorders they may have. Screening tests are done on both the parents and the foetus to check for certain genetic disorders.
● Carrier screening is a test done on both parents. If both parents have any genetic disorder or are suspected to be carriers (someone in their family could have the disorder), then this test helps determine if they are indeed carriers of the defective gene. It is best to take this test before trying to get pregnant.
● Prenatal genetic screens are tests taken in the first and second trimester as well. These are blood tests performed on the mother to check for certain disorders. Ultrasounds on the baby will also be performed during this time to check if the baby is at risk of having certain disorders.
● Non-invasive Prenatal Testing checks the DNA from the placenta. Instead of drawing samples from the placenta, this test will check the placenta found in the mother’s blood to screen for certain abnormalities.
Routine diagnostic tests during pregnancy help identify if the baby is at risk of certain genetic disorders. These procedures also carry a small risk of complications to the pregnancy. So, the doctor will not suggest these tests unless they suspect the baby is at a high risk of certain disorders.
● CVS - Chorionic Villus Sampling takes a sample of the placenta in the first trimester.
● Amniocentesis takes a sample of the amniotic fluid in the second trimester
● PUBS – Percutaneous Umbilical Blood Sampling tests the blood from the umbilical cord and is done only if amniocentesis and CVS are not possible.
● CMA – Prenatal Chromosomal Analysis is a more advanced test done on cells taken from amniocentesis or CVS to check if the chromosomes have any abnormalities in them.
● WES – Whole Exome Sequencing checks almost all the genes of the baby in case of complex conditions.
Genetic disorders in pregnancy are unavoidable in most cases. Genetic counselling, screening and diagnostic tests can help identify issues at the earliest and deal with them in the best way possible. Ensure you talk to your doctor about these options if you are worried about genetic disorders in your pregnancy.
Genetic disorders can cause miscarriage, stillbirth, preterm delivery or even complications during pregnancy. It can increase the risk of genetic disorders being passed on to the baby.
Genetic disorders can pass on to the baby and have a similar, greater or even lesser impact than it did on the parent. It can cause physical deformities or intellectual disabilities which may not be visible right away.
Genetic disorders can affect a woman’s ovulation, and fertility, or even cause malformation of the female reproductive system, making it difficult to conceive naturally.
No, not all genetic issues can be screened for. Today, screening and diagnostic tests can identify certain disorders and others may not be visible until the baby is born and starts developing skills.
