Prenatal Testing: better prospects ahead

With the introduction of prenatal genetic testing in the 1960s, the element of uncertainty has gone down significantly

Conceiving a baby is one of life’s biggest dreams for most couples. But when the offspring is born with a major genetic disease, it can be a challenging situation demanding time, money, and emotional strength on the part of parents. This was the case until the 1960s when couples were not aware of any abnormalities their children may have. However, with the introduction of prenatal genetic testing in the 1960s, the element of uncertainty has gone down significantly. Detection of chromosomal abnormalities through prenatal screening has been in the offing since the last 40 years – the first time through amniocentesis in the early 1970s. These genetic tests let parents know whether their unborn child is likely to have any abnormality. However, they did come with their own set of challenges. Amniocentesis was often not recommended by physicians except in specific cases given the minimal risk of miscarriage due to its invasive nature.

Cut to 2020, and genetic testing technology has expanded the scope of prenatal testing immensely. The technology available today ensures that the medical procedures are not invasive in nature. They are based on a more accessible fetal DNA source, the mother's bloodstream. It is possible to put together a complete genome sequence of an unborn child using these DNA fragments. Any genetic analysis done after birth can now also be done in the fetus, in the first trimester itself. Screening for a broad range of conditions is becoming a routine aspect of prenatal care.

The Indian scenario

India’s birth rate currently stands at about 27 million annually. However, a country with such a high birth rate also has an infant mortality rate of 9 million deaths per annum.1 Among the other causes, genetic and congenital abnormality hold the second spot when it comes to childhood mortality in India – and prenatal screening can emerge as an answer to lowering this death rate if done regularly. Traditional screening methods such as amniocentesis, and chorionic villi sampling occupy about 60% of the prenatal test market in India currently.2 However, given their invasive nature, many mothers choose to opt out. This is where non-invasive techniques are becoming a gamechanger. They not only detect fetal problems in the early stages but do so without posing a risk to the baby.

Estimates suggest that the prenatal screening and diagnosis market will grow significantly as early as 2024.3 Some major techniques available today across Tier 1 and 2 Indian cities include ultrasonography and maternal serum screens; blood tests for select trisomy or non-invasive prenatal testing (NIPT). NIPT is already emerging as a highly preferred technique given that it is safer and faster, and more reliable. Other non-invasive prenatal testing methods such as pre-implant genetic diagnosis (PGD) have been accepted in major IVF centers in the country. They help in sampling of cells from human embryos before implantation. Another test that has gained popularity is called the Nuchal scan, or ultrasound detection. Done in the first and second trimester, this method helps in identifying higher risks of Down’s syndrome. In fact, through carrier screening, a genetic test, it is possible to determine whether a healthy person is a carrier of a recessive genetic disease. It can help understand the likelihood of an individual's reproductive risk and that of having a child with some genetic disease.

Although non-invasive prenatal testing has many advantages, given the diversity in income among the Indian population, these techniques are somewhere limited to the major Indian cities. As more people become aware of the prevalence of genetic abnormalities, the acceptance of newer screening techniques is likely to increase.

The way forward

The future holds immense possibilities with tests that cover diseases which cannot currently be predicted with complete accuracy. Genetic testing is now an integral part of several clinical specialties and this is only likely to increase in future. However, for the benefits to percolate deeper, this must be accompanied by better awareness of the potential of non-invasive prenatal screening techniques and higher lab standards.

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Prenatal screening Dheeraj Jain


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