Pre-implantation genetic diagnosis is still effective

Oladapo Ashiru
| credits: File copy

This topic was borrowed from a recent publication from the Journal of Fertility and Sterility; and from the pioneer of Pre-implantation genetic diagnosis worldwide, Dr. Alan Handyside.

I receive calls on a regular basis from people asking the question, “Do we do PGD in Nigeria? “Can we help sickle cell carrier or those who want to balance their family?” The enquirers say they ask because some doctors had told them that PGD is not done in Nigeria.

However, we are able to affirm that the procedure is available in Nigeria due to our pioneering effort in this area in the entire West African region. The application of pre-implantation genetic diagnosis and pre-implantation genetic screening, commonly referred to as PGD and PGS techniques respectively, were initiated in our fertility clinic in 2009, and has resulted in the birth of healthy babies, especially without sickle cell anaemia. This was published in the recent edition of the Nigerian Medical Journal by Okeke, Ashiru, et al (2013).

What is PGD?

PGD is an acronym for Pre-implantation genetic diagnosis. It refers to the techniques used to check for genetic defects in embryos created through in-vitro fertilisation before pregnancy. It refers specifically to when one or both genetic parents has a known genetic abnormality and testing is performed on an embryo to determine if it also carries a genetic abnormality.

When used to screen for a specific genetic disease, its main advantage is that it prevents abortions, as the method makes it highly likely that the baby will be free of the disease under consideration.

Who can benefit from it?

Candidates for PGD include couples that both have sickle cell trait (AS) and want children without sickle cell disease (SS). Also, couples with a history of recurrent miscarriages can make use of the process. It is also good for mothers who are above 38 years or those with a past history of having a baby with Down’s syndrome.

Again, couples who want to balance their family in terms of sex; or couples with family history of genetic diseases such as cystic fibrosis, haemophilia, muscular dystrophy and others; as well as couples with repeated IVF failure and severe male factor infertility can benefit maximally from PGD.

What does it entail?

The story of one of our patients at the Medical Art Centre, narrated here, gives you an idea of the process: “John and I married when I was 31 and he was 33. We had been dating for four years and many people had advised us not to marry. In fact, neither his parents nor mine approved of our relationship as we were both AS. They were afraid that we would have SS children who would have the sickle cell disease. However, after dating on and off for four years, we decided to take our chances, as we could not find anybody else we wanted to be with more than each other. “I read somewhere that for each pregnancy, our chances of having an SS child was 25 per cent, an AA child was 25 per cent and an AS child was 50 per cent. Perhaps it was foolish of us, but after long and anguished debates, we decided that we would take the risk.

“It was only when we got married that I first met a child who had the sickle cell disease. He was the five-year-old son of our next door neighbour. I saw him having a crisis when I visited his mom in their flat. He was lying on the sofa, screaming in pain that his legs and joints were hurting, his eyes were yellow and his chest was large from an enlarged spleen.”

The scientific explanation, so far, is that when the sickled blood cell blocks the flow of blood through the small blood vessels, it causes damage to the lungs, which causes respiratory problems and also acute pain episodes in the arms, legs, chest and abdomen of the patient. It can also cause stroke, prolonged and painful erection (priapism) and damage to most of the organs, including the spleen, kidneys and liver.

Damage to the spleen makes sicklers, particularly the children, prone to bacterial infections which totally overwhelms them so that they are constantly sick and in pain. Nevertheless, with good medical care, some have lived up to 60 years and above.

Mrs. John continues her story: “If I had seen somebody going through the sickle cell crises before I was married, I might have made a different choice. It broke my heart to see this little fellow in so much pain. From then on, I grew cold feet about conceiving and bringing a “sickler” into the world.”

The sickle cell disease, a disorder of red blood cells, is mainly found in Africans and African Americans, and it is inherited from the parents.

People with sickle cell disease have abnormal red blood cells that have haemoglobin S, which sometimes become sickle or crescent in shape, making it difficult for the blood to pass through small blood vessels. When the sickle blood cannot pass through the small vessels, then blood cannot get to those parts of the body which the arteries serve. Eventually, these tissues become damaged due to lack of oxygen and other nutrients. These damaged organs and tissues lead to the complications of sickle cell disease.