Sickle cell, gender selection can be addressed with technology – Danga
The prevalence of sickle cell anaemia is high in Nigeria and Sub-Saharan Africa, but access to necessary genetic testing and remedies are limited. In this interview, CHRISTOPHER DANGA, a medical doctor with specialization in reproductive health garnered from over 40 countries, shares his experiences with BusinessDay’s OBINNA NWACHUKWU in Abuja.
How and why did you develop interest in sickle cell anaemia?
To be very clear about my interest in this field, it is actually because of the prevalence of the sickling gene in Africa and in the world generally. But Africa has the highest number of cases of sickle cell anaemia. And in Africa, Nigeria stands out. It stands out because of the population, so the prevalence of sickle cell anaemia is high in Nigeria. In the past, a couple about to get married will be counseled by either the geneticists, or in the hospital. And then they will be discouraged from getting married because of the sickling gene.
If you go to the religious aspect of it, you’ll find out that the pastor or the Imam will want your genotype tested, and if you and your intending husband happen to be careers of the ‘AS’ gene, the chances of having an ‘SS’ is 25%. So, we’ve seen all these things on ground.
The basic interest is that we know prevalence is high in Africa and Nigeria in particular because of the population. But then, why shouldn’t couples who are intending to get married get married if there is a solution? So that is one of the drives. And you know that I am in the reproductive medicine, that is, NISA premier hospital reproductive medicine running the IVF procedures, so we look at such cases where intending couples come in with the career gene ‘AS’ , and our drive is not just to give them a child, but to give them a healthy child. So, this is the reason we moved into this sector
In Africa, it is common for couples to desire to have a male child, the absence of which often leads to fighting and in some cases divorce. Based on your field and experience, is there any solution to the issue of gender enhancement?
Yes there is but we try as much as possible to discourage it. Because nobody has the right to decide what kind of gender you want to bring into this world. However, gender enhancement is done in so many countries in the world. And so we have that technology on ground, but we will prefer if it’s based on medical reasons, in the sense that some families may have some sex-linked diseases. So you want to select a particular gender.
Haemophilia is one of the sex-linked diseases, so if it affects a particular sex in the family, you would want to go to the opposite sex. But, as for gender enhancement or gender balancing, we have the technology to be able to choose male or female. And of course, not just choosing the sex of the baby, but also choosing a healthy baby. Because for some people their concern is about the sex of the baby, they don’t look at the other chromosomes, are they healthy male and healthy female? In this aspect of our technology, we are able to check across all the chromosomes, to know whether it is a boy or girl as the case may be, and whether it’s a healthy boy or healthy girl, because we have to check all the chromosomes.
How do you do that?
It is the same thing as the sickling gene, when the embryos or eggs are harvested from the woman and mixed with the sperms and generate embryos after you remove the cells from the embryo, you’re able to check if it is a male embryo or woman embryo. And so we only carry the male embryo and transplant since that is the desired sex, that’s family balancing if you like.
Are you therefore saying that if a couple wants a male child you can assist them get a male child?
Very well, from their embryos we are able to sort out which ones are male. A family with so many girls, or so many boys and wants a girl, why not, because your husband sperm has the chromosomes, X Y, and the woman has the chromosome XX. So when they meet together, there are embryos that are XX and there are embryos that are XY, So those embryos that are XX, one of the chromosomes coming from the male X and then the other one coming from the female X, so both XX is now female. But if the man releases the Y chromosomes and the Y chromosomes bind with the X chromosomes in the woman, that is XY you have a male. For a family where you have so many boys and you need a female, we will be looking at the embryos that is XX.
Over time, the impression has been created that if a couple both have ‘AS’ genotype, they must end up with an ‘SS’ child. Are you saying you have the technology to change that too?
Yes, we have a technology that changes the situation. The couple mustn’t end up having ‘SS’ children. No! When two ‘AS’ adults want to have children, the chances of having an ‘SS’ child is 25%. And the chances of having an ‘AA’ child is also 25%. But the chances of having ‘AS’ child is 50%. So you can see that the ‘AS’ is higher, but God forbid you have ‘SS’, it’s quite significant.
So it’s not a must that when two of you are both ‘AS’, you must have an ‘SS’ child, no. We have a technology we can use to check the chromosomes of embryos. Usually when couples come to an IVF centre and they want to have a child, the gametes from the man and the woman, that is, the eggs and the sperm are fused together to generate embryos. As these embryos are growing, you can take out cells, and check if that embryo that is growing will result to either SS, AS or AA as the case may be. So we use this science which we call the pre Implantation Genetic testing, to see how we can determine the error. So this is more of a preventive measure that we take.
If you go to a genetic centre like ours right now, and you want to find out what this component of the embryo is made up of, you get the embryos of the couple that they have generated in an IVF centre, and you bring it. We biopsy it, we remove the cell, bring it to the genetic lab, and extract the DNA. Once it’s extracted, it is amplified to increase the size, the numbers of that. And then, because we know where the genetic error is, we’ve designed the primer that goes in there to bind that part that has the genetic error.
So that area is now amplified and we’re able to know the region where that error is. So we use a technique called the polymerase chain reaction, PCR to amplify that site. And once that site is amplified, then we use a mini sequencing technique to sequence that area. So, once you copy that area, you’re able to know where the particular error is, or if it is not there. If you do that on embryos, it means that, that embryo that has a genetic error does not have the chances to go back, and is not transferred, but the one that is free from the genetic error can go back
What has been the result so far?
The success is enormous. This technology is unique, sensitive, and at the same time very trusted in the sense that when it comes out, the chances of having error is less than 5%. So, the success is, when you do it, the result that comes out will either be AA, AS or SS as the case maybe . So, as you can see there is a solution on ground and the success have been quite commendable.
Is this solution only for those that come for IVF, or does it include those that copulate naturally?
Because ours is more of preventive, it is for people that opted for IVF because you can only generate the embryos and get out the embryos outside the human system when you go through IVF. At the same time however, it’s also available for those who already have conceived and want to know if the baby is a sickler.
For this later group, it is not a preventive measure, although it could be said to be a preventive measure but they are already pregnant so it is called pre natal and not pre implantation. The first one is pre implantation when you check the embryos before they implant, but with this, the woman is already pregnant, and wants to check the status of the baby, if it’s a sicklier, a carrier or a normal child. If after checking and the baby is affected, i.e a potential SS, the options will be to either abort or discard the pregnancy.