Creating The Perfect Genetic Match

Political correctness does not cut it here. Diversity is the anathema. Slight differences can be dangerous, even fatal. In the quest to find a stem cell donor for a patient who needs a transplant, it is all about matching for every racial, cultural or conceivable stereotype.  Siblings have a 25 percent chance to be perfect matches for one another and are the first source tested. Some people are not content to play the numbers game. They would rather play an active hand and create the perfect match.

Before we travel through genetic match-making, a quick refresher on why this is all relevant. Many patients with cancer go on chemotherapy to destroy their cancerous cells. While chemo does kill the bad cells, it can be a bit reckless and take out healthy cells too.  To replenish these healthy cells, patients are often given stem cell transplants following chemo. Stem cells are special cells with the retained ability to become any cell of the body. If chemotherapy is a forest fire set to kill some ravenous and deadly weeds, a stem cell transplant is the subsequent sprinkling of new seeds to reforest the burning green.

How good a match is tells us the genetic degree of fit between a donor and recipient. Finding (or creating) the right match is central to a successful stem cell transplant. The reason is pretty intuitive. The immune system in each of us is designed to thwart any attempts by foreign cells, such as bacteria or fungi, to lodge themselves in our bodies. If a stem cell transplant is done with donor cells that looks foreign (remember, no political correctness here), the host’s immune system will set into motion. What follows is a chronic condition called graft versus host disease where the host fights off the donor cells. Sounds a bit like what is happening to Indian nationals in some sunny parts of the world.

Apart from dialling down the immune system to let the donor cells engraft, physicians seek more ‘like’ cells. Perfectly matched cells will slip by the immune system of the host.  These cells are treated as part of the family and allowed to settle. Gradually they may take over the burnt-out host and give a patient a new lease on life.

What are the options for a child with a terminal disease and no close matches in the family? Some families decide to have another child through in vitro fertilisation or IVF.  IVF is a technique to fertilise sperm and eggs outside the body. The fertilised embryo is then implanted into the mother who goes on to have a normal pregnancy. To create a perfect match, parents go through IVF but select only those embryos that form a perfect match for their sick child. This process is called preimplantation genetic diagnosis and is approved in the UK at a handful of medical centres. Yes, people across the world are actually giving birth to save existing children from incurable diseases.

Many countries, including India, outright ban any form of prenatal diagnosis, as it can also be used to determine the sex and other genetic qualities of a child. 

There is a solution that would preclude the need to create the perfect match when there is none in the family. It is the development of a national matched unrelated donor programme. Dr. Mammen Chandy runs one of the main transplant programmes in the country at the Christian Medical College in Vellore. He confirms that in India stem cells are only collected for transplants when the donor and patient are related. Many countries such as the US have very successful programmes through which the public can submit their cell type that is then entered into a national database. If a patient needs a donor of the same type, the programme contacts the closest match and requests them to donate some cells.  
India should aspire to be a superhero, not a superpower. Stem cell transplants save lives. A national matched unrelated donor programme open to the world would be a pretty heroic thing to do.  

Dr Kumar, and our health team, can be contacted at health.forbesindia@network18online.com