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Genetic Complications During Pregnancy: Importance Of Early Detection

Genetic Complications During Pregnancy: Importance Of Early Detection
These tests are performed using a sample of blood, hair, skin, amniotic fluid (the fluid surrounding a fetus during pregnancy), or other tissue. The clinicians may also perform a procedure called a buccal smear.

The term 'birth defect' encompasses a diversity of health conditions some of which are externally visible, while some require diagnostic methods to confirm.

Written by Editorial Team |Updated : December 1, 2021 2:15 PM IST

A congenital disorder (CD), also known as a birth defect, occurs while the baby is still in the womb. In India, genetic disorders are the third most common cause of mortality in newborns. The severity of the disorder varies depending on their nature and location. For some, the condition may not manifest until much later in life, if ever, and at other times, the disorder is incompatible with life. In India, about 60 per cent of pregnancy losses, 2-3 per cent of all neonatal mortalities, 50 pr cent of childhood deafness, blindness, mental retardation and 1 to 10 per cent of all malignancies are directly due to genetic factors. In fact, more than 1.7 million children are born with birth defects every year.

The term 'birth defect' encompasses a diversity of health conditions including physical malformations such as cleft lip or palate, chromosomal abnormalities such as Down syndrome, functional defects, congenital deafness or blindness. Some birth defects are externally visible, while some require diagnostic methods to confirm.

Reasons for genetic defects

The fact remains that genetic problems can happen to anyone or anybody in the population who plan to have a baby. However, the probability of genetic problems are higher in couples who are iin a consanguineous marriage, which means marriage between closely related individuals, between first or second cousins, maternal uncle niece marriage, etc. In such cases, there is a higher risk of a genetic mutation causing genetic problems. There is added disadvantage as their parents or their siblings may have also married similarly. The risk of genetic problems is higher in families with a history of a genetic disease and it is also elevated in couples planning late as they are more likely to pass down imperfectly duplicated chromosomes.

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Genetics and chromosomal abnormalities

If chromosomes may be compared to a wall, the genes are the bricks that make up the wall. A single gene defect can be lethal. They usually may not cause the chromosome structure or number to be abnormal. Similarly, a person can have normal genes, but, because they have extra copies of chromosomes or abnormal structure of the chromosomes, they can end up having a major chromosomal abnormality.

Common genetic disorders

The chromosomal abnormality occurs when there is one copy instead of two. This is called monosomy. It can also happen if there is an additional copy of a chromosome (i.e. three copies instead of two). This is called a Trisomy. Health and development issues can appear due to these abnormalities. These chromosomal abnormalities may cause disorders like -

  • Down syndrome
  • Heart defects
  • Kidney abnormalities.

With genetic problems the child can have low IQ, speech disability, hearing disability, developmental delay leading to constant hand-holding and special needs for rest of the child's life.

Importance of family history and investigation

In these cases, appropriate investigations and consultation are needed for the couple before planning a pregnancy. A detailed family history and targeted investigation is the way forward. It is optimal for the couple to wait for the results to arrive for identification of possible genetic issues that a young couple may have to encounter. If there have been cases in your family of any of these concerns, then you must convey it to your primary doctor. The most common issue that most gynaecologists face is the lack of information that the young couple may have about their extended family and the cause of the loss of such family members in the past. In cases of possible genetic issues, the primary doctor could refer the couple and affected family members to a geneticist or fetal medicine expert. In turn, they can prescribe targeted tests that will help in diagnosing the genetic defect.

Effectiveness of post pregnancy tests

If the woman is already pregnant, a similar test can be performed using placental tissue or amniotic fluid sample. Therefore, doctors can diagnose if the fetus is affected or not as early as 1st and 2nd trimester. The first trimester double marker and second trimester quadruple marker blood tests are done to screen pregnant women for major chromosomal abnormalities like Down syndrome or Patau syndrome. These are not diagnostic tests and cannot confirm if the fetus is healthy.

Genetic tests and their importance

In the past few years, genetic testing has emerged as an advanced tool to understand genetic conditions and is increasingly being accepted as a tool for reproductive health analysis.

  • A genetic test helps identify changes in chromosome number or genetic mutations in genes which confirms or excludes a suspected genetic mutation.
  • This in turn determines a person's chance of developing or passing on a genetic disorder to their children.
  • A pregnant woman can undergo prenatal diagnostic testing to confirm the genetic makeup of their child.

Options for couples with defective genes

If one is well aware that if both parents carrying defective genes, it may be passed on to the fetus with very severe consequences. Such parents who may have had children who have died due to the genetic condition, can consider options like embryo donations. This will give an opportunity for prospective parents to have a healthy baby with no genetic abnormalities. Many couples also have an option for adoption after learning the severity of the genetic disorders.

Genetic issues in the child causes social, physical, emotional and financial strain to the parents and their close family. Depending on the severity of the disease, some children born with defects die within a few years of birth and some may live for 20- 30 years. There are cases of broken families, divorces, domestic violence and suicide because of these issues. Birth Defects have been recognized globally as a major contributor to neonatal and infant mortality and disability. Being aware of the impact of birth defects on our future generation and implementing a strategy for their prevention, early identification and management are therefore of utmost importance.

(This article is authored by Dr. Anju Namashivaya, Foetal Medicine Specialist, SPARSH Hospital for Women and Children)