Hyderabad: Prescribing genetic tests at a certain stage of pregnancy for women in public and private healthcare institutions has become universal in Hyderabad. Almost all obstetrics and gynaecologists ensure that genetic tests are carried out before the foetus is fully formed.
Such genetic tests have become even more vital to check for recurrence of ailments among couples whose first child is struggling with an untreatable ailment that has originated from chromosomal abnormality or genetic defect. In such situations, genetic tests have the ability to predict the probability of whether the next child of the couple will carry the same disorder as the first child. According to doctors, risk of such repeat of genetic disorders among offspring is anywhere between 25 per cent and 50 per cent.
Tests empower couples
Genetic diagnostics has reached a stage where tests can accurately, if not with pin-point precision, predict the probability of parents or offspring passing their hereditary genetic defects. Such tests empower couples who are either waiting for their first child or planning to have one more child, with enough information that would enable them to take informed decision. In case, the genetic tests indicate that there could be birth defects, then the couple can opt for medical termination of pregnancy.
There are 46 chromosomes and up to 25,000 different genes in the human body. And, so there could be abnormality in every chromosome. As far as gene-level defects causing genetic disorders are concerned, there are anywhere between 6,000 and 7,000 different diseases.
So, practically it is not possible to screen out all the ailments and that’s the reason why obstetricians prescribe genetic screening tests for most common kind of ailments. The consensus among the doctors is that it is better to conduct such tests and there is a definite need to provide them universally to all pregnant women.
Among the chromosome level issues, the commonest disease that a couple can get tested include Downs Syndrome, Trisomy 13 also known as Patau Syndrome (due to the presence of an extra chromosome 13 in every cell), Trisomy 18, which is also known as Edward’s syndrome due to abnormal amount of chromosomes in the cell.
Apart from the above genetic defects, another medical condition that is very common among Indian sub-continent is thalassemia and sickle cell anaemia. On an average, one in every 25 people in India is a carrier of thalassemia and it’s on a higher side. Every year, anywhere between 10,000 and 12,000 children are born with thalassemia, indicating pretty high numbers for India.
Another common genetic ailment is Spinal Muscular Atrophy (SMA) in which babies become floppy i.e. they can’t summon muscles to do activities. According to doctors, there is a breakdown of communication between nerve cells in the brain and spinal cord, as a result of which the brain stops sending signals to control muscle movement.
Doctors advise couples to get genetic tests done before they decide to go for a child or even in the first trimester. “In some western countries, testing for thalassemia, which is a very simple test, is done even before marriage. In India, couples can go for this test before pregnancy or at least in the first trimester (which lasts until end of 12 weeks) of pregnancy,” advises Head, Genetics, NIMS, Dr Prajnya Ranganath.
List of genetic tests
The most common kind of genetic tests existing today are amniocentesis and chorionic villus sampling (CVS), which are carried out to check whether the foetus has ailments such as Downs Syndrome.
CVS test is usually done between 11 weeks and 13 weeks, and, involves collecting a small amount of placenta, which contains same kind of genetic tissue as the foetus. Amniocentesis is a minor procedure that involves removal of amniotic fluid, which surrounds and protects the baby during pregnancy, from uterus.
Although doctors advise for universal genetic testing to all pregnant women, at present, such a measure is not possible because of cost factors. Compared to traditional tests such as an ultrasound, taking up genetic tests is relatively expensive.
In fact, except for NIMS, where charges for diagnostic tests are affordable compared to corporate hospitals, no other public healthcare facility in the State offer such tests for free. Public health experts said that since the number of pregnancies in Telangana and elsewhere was high, the chances of infants born with genetic diseases was also high. Once infants are born with such untreatable medical conditions, parents have to endure a lifetime of burden.