Hereditary disorders can now be detected in a test-tube embryo in India and abortion avoided.

Thirty-five-year-old Amrita Kaur's (name changed) nephew has Down's Syndrome. It's a mental disorder (stunting) with malformation of physical features (fingers and face). Part of a joint family, she has witnessed how this disorder daily challenged the coping mechanism of the entire clan. Though desperately keen on a sibling for her five-year-old daughter, she dithered about a second pregnancy, since Down's Syndrome is genetic.

Then Mumbai-based fertility experts Aniruddha and Anjali Malpani offered her the preimplantation genetic diagnosis (PGD). Amrita allowed herself to be demystified over this latest in ivf or in-vitro fertilisation technology which blends molecular genetics with assisted reproductive technology.

Ten weeks into pregnancy, with the guarantee of a healthy foetus tucked into her womb, she has finally acquired that happy glow of all mothers-to-be. It is only incidental that she is also the first woman in Asia to have been subjected to this technology.

PGD is directed at a narrow group of couples at high risk of passing on certain genetic disorders. The long list of genetic diseases (35 to 50) which can be checked through embryo biopsies include cystic fibrosis (a kind of respiratory and pancreatic disorder), thalassaemia (a form of anaemia more common in India), spinal muscular atrophy, Tay-Sachs disease (mental retardation brought about by too much inbreeding), sickle-cell anaemia, polycystic kidney disease, Huntington's disease, autism (inability to communicate with others) and vitamin D-resistant rickets, among others. The technology relieves couples from the wrenching choice of abortion if defective embryos have been implanted. Only about 20 centres worldwide have this expertise, with 200 pregnancies reported.

This is how it works. IVF (its meaning "in glass" gave the popular perception of a baby being spawned in a test-tube) involves marrying the eggs (ova) from the mother with sperms from the father within the sanitised confines of a lab before safe transfer into the womb. The embryo grows cell by cell. In the blastomere method of PGD (which the Malpanis favour), just a few days after fertilisation, one or two cells are removed from this embryo - by a micro-pipette as delicate as human hair. This cell is checked for genetic defects in the family of the couple whose children stand a high chance (20 to 50 per cent) of acquiring the disease. In just 24 hours the couple would know whether the fertilised embryo is free of the defects, fear of which has been affecting their happiness. When the all-clear is received, the healthy embryo is implanted in the uterus.

The Malpanis began setting up the PGD centre four years ago, roping in UK-based Alan Thornhill (who had assisted Alan Hayside, the first expert in the world to have conducted PGD a decade ago). And they are still learning. The entire process takes six to eight hours, says Aniruddha, and grins: "My hair has turned grey since I started work on this." The couple have conducted five PGDs till date. There is also the high cost involved in the import of technology. Avers his wife Anjali: "It's still to reach the stage where a phone-call could get you all the stuff needed. If a probe (used in screening the cell) is not properly handled, it will have to be discarded. And it costs several thousand dollars."

Aniruddha predicts that eventually one embryo biopsy would routinely screen the would-be human for all the known genetic disorders. (Today, the process is still specific to the anticipated problem. For instance, a couple with a family history of thalassaemia would be concerned only with finding out if this problem will plague the implanted embryo.) And that may not be a fantasy. A fortnight ago Dagan Wells and Joy Delhanty of University College, London Medical School, reported that they had devised a way by which the entire range of chromosomes (those chips of genetic information) in a test-tube embryo may be checked.

Before PGD, couples who feared genetic disorders in their offspring had to be content with amniocentesis (screening a cell from the amniotic fluid of the womb) or chorionic villus sampling (which involves samples of the early placenta - the food link between the mother and the baby. Both tests can be done only after pregnancy is established. A couple which finds out an abnormality in the foetus at this stage faces the crushing choice of abortion. Equally agonising is the situation of continuing with such a pregnancy - that is, if their religion forbids abortion.

However, PGD is a developing technology and, therefore, its success rate is only 20 per cent, concedes Aniruddha. Another deterrent is the cost: about Rs 1.5 lakh (in the US it is between $3,000 and $15,000). But this must be weighed against the expenditure not just in financial terms but also the strain of bringing up a child with birth defects. Some ground their arguments against this technology in religious and legal ethics. But it's a thoroughly subjective debate.

There are also fears that cells destroyed at the embryo level - ones that are taken out for diagnosis - may leave the adult vulnerable to certain diseases which may surface later. But this fear has no scientific basis, maintain the Malpanis.

The Malpanis also have to grapple with the primitive fear in the minds of most couples that removal of a cell from an embryo may, while opening a desperately needed window to its health, leave the foetus somehow incomplete. Explains Anjali: "Some are afraid that removing a cell may maim the embryo - deprive it of an arm or a leg. But that's not how nature works."

Another more concrete risk is that of misdiagnosis. The international PGD consortium last year reported four cases of misdiagnosis and cautioned the medical community "to continue to improve our techniques and build in extra safeguards".

This new technological revolution of sorts will, therefore, not merely spawn bawling babies but is also bound to give birth to a strident and controversial debate. But if we jettison technology without examining its complete potential, we may be guilty of, well, throwing the baby out with the bath water.

Authored by : Dr Aniruddha Malpani, MD and reviewed by Dr Anjali Malpani.

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