Sickle Cell Disease: Genetic Factors

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Sickle Cell Disease: Genetic Factors




Guest:  Dr. Sherron Jackson – Pediatrics - Hematology/Oncology

Host:  Dr. Linda Austin – Psychiatry


Dr. Linda Austin:  I’m Dr. Linda Austin.  I’m talking, today, with Dr. Sherron Jackson who is Associate Professor of Hematology/Oncology at the Children’s Hospital here at the Medical University of South Carolina.  Dr. Jackson, you have been an expert for many years in a very serious and significant illness, sickle cell anemia.  When you explain to parents for the first time just what this illness is that they may bring a child in with, how do you explain it to them?  What is it?


Dr. Sherron Jackson:  I generally explain that this is a congenital disorder.  Most of the families that I meet nowadays are new parents whose infant has been diagnosed from newborn screening.  I explain that this is a condition affecting the red blood cells of the body, the parts of the body that are responsible for carrying oxygen to all the tissues.  And I explain that the hemoglobin in these red blood cells is different, and because of that genetic difference, the babies and children are susceptible to changes in the red blood cells, the sickling, they call it.  That describes the shape of the cell.  Instead of it being a round donut-like shape, the blood cells actually take on a crescent moon shape that makes it difficult for those blood cells to travel through the blood stream.


Dr. Linda Austin:  Now, when the cells have that difficulty in traveling, why does that create problems for the child?


Dr. Sherron Jackson:  The problem is in the very small blood vessels.  The diameter is just enough to carry one blood cell, one round blood cell.  So, when there are a number of the sickle, or crescent, cells clumped together, they do not flow through the blood stream as they normally would.  And this renders injury to the tissues, injury to the blood vessels, and it ultimately results in pain in those parts of the body.  Many in our community have heard of sickle cell disease and have associated sickle cell with some kind of painful symptoms and painful episodes.


Dr. Linda Austin:  Now, you say “in our community” because this is most commonly an illness of African-Americans?


Dr. Sherron Jackson:  That’s exactly right.  Predominantly, African-Americans will carry the sickle gene, sickle trait, we say, and have the tendency to pass that gene on to their children.  When a couple has a child, if each parent has trait, there’s a 25 percent chance that the gene gets passed to the children.  The condition doesn’t just affect African-Americans.  But, in our country, it’s predominantly those of African heritage.  But we find sickle disease in other ethnic groups, particularly those who are from the Middle East and the Mediterranean countries, as well as South America.


Dr. Linda Austin:  Now, when a parent has a child with sickle cell anemia, does this come as a shock to them, that they may have no idea that they actually are carriers of the trait until their child is born?


Dr. Sherron Jackson:  Exactly.

Dr. Linda Austin:  Or will they often have cousins with sickle cell anemia?


Dr. Sherron Jackson:  Well, because of our high incidence of sickle trait in the low country, there are many families who know of someone in their family that has sickle trait or sickle disease.  So, I think persons in our community are a bit more aware because they do have family members with sickle disease or sickle trait.  But I’m often surprised at the number of new families that I meet where the parents have a baby with sickle disease, but neither parent is aware that they have sickle cell trait themselves.  So, it’s a shock to them that their new healthy baby has been diagnosed with a chronic condition.


Dr. Linda Austin:  So then, if a person has, let’s say an aunt, uncle, cousin or a grandparent who had sickle cell anemia, would you recommend that they have genetic testing before they get pregnant, just so that they are not taken by surprise?  How would you counsel a person?


Dr. Sherron Jackson:  Absolutely.  We would recommend any adults in our community, women and men, especially African-American women and men, but anyone, really, should have the opportunity to do screening for sickle cell trait so that we can identify persons who may have children with sickle cell disease.  There are opportunities for adults to be screened at no charge in our community.  And, if you’re ever attending a health fair, there will often be a booth set up for sickle cell trait testing that our DHEC, our state health agency, sponsors.  This is one way that we can identify adults who have sickle cell trait in the community, before they have children. 


Dr. Linda Austin:  So, if somebody is listening to this podcast and is interested in getting screened, at no charge, is there a number they can call?  Who should they contact?


Dr. Sherron Jackson:  The COBRA Foundation is our local sickle cell agency.  This is a community organization that will provide the screening, sickle cell trait screening, free of charge.


Dr. Linda Austin:  Dr. Jackson, do you know the telephone number to call for someone who would like screening for sickle cell anemia?


Dr. Sherron Jackson:  Yes.  The phone number for COBRA is (843) 225-4866.


Dr. Linda Austin:  Thank you.  So then, let’s imagine that a young woman is thinking of getting pregnant.  She gets screened.  In fact, she has sickle cell trait.  What would be the next step for her to take, to evaluate her real risk?


Dr. Sherron Jackson:  Once we know that an individual has sickle cell trait, and especially women of childbearing age, but women and men, we would recommend that they have counseling through the COBRA Foundation.  It would be an opportunity to give them information about the risks and the chances that their child would have sickle cell disease if their partner has sickle cell trait. 


It’s sometimes confusing because the persons with trait are completely healthy and do not have symptoms of pain or anemia, which we associate with sickle cell disease.  And sometimes individuals will be concerned that there’s something wrong if they’re diagnosed with trait.  But, really, the main emphasis is on educating a person, if they have trait, to make them aware of their potential for having a child with sickle cell disease.  But there would not be any symptoms or episodes of illness in a person who has sickle cell trait.


Dr. Linda Austin:  And if, let’s say, a woman or a man has sickle cell trait, which means they’re a carrier but not affected, and they marry someone who does not have trait, they could produce a child who might have trait, or might not have trait, but they would not produce a child who has sickle cell anemia, is that correct?


Dr. Sherron Jackson:  That’s correct.  It would take two parents, each parent having sickle trait, having a sickle gene, having a child together.  And, again, even for that couple, every pregnancy carries a 25 percent chance, so there is the possibility for the couple to have a baby with sickle cell disease.  The baby could have sickle trait, or the baby might inherit each parent’s healthy, normal, genes and not have sickle disease or trait.  But, we want families to understand that there is the 25 percent risk of having a baby with sickle disease if each parent has sickle cell trait.


Dr. Linda Austin:  What percentage of African-Americans in the low country carry the sickle cell trait?


Dr. Sherron Jackson:  We have a higher incidence of trait in the low country than other parts of the United States.  Sometimes we believe it’s as high as 10 percent, or even 12 percent, in our community, so we have the expectation that we may have more children born to couples, living in the low country, that have trait.


Dr. Linda Austin:  So, if I were to quickly do the math on that, let’s say a woman has trait, she would have a 10 percent [chance] of finding a man who might have trait, and then they would have a 1 in 4 chance of having a baby with sickle cell anemia.  So, her chances would be 1 in 40 if he were untested, correct?  Is that right?


Dr. Sherron Jackson:  That’s right.


Dr. Linda Austin:  Okay.


Dr. Sherron Jackson:  And, often, the males in the community are less likely to be screened.  Most of the women of childbearing age are screened at a pregnancy visit during the early trimester, first trimester, of pregnancy.  And, of course, at that point, we really would like to know if the partner, the husband, has been screened, and we need to know if that individual has sickle trait.  But, it’s very difficult sometimes to get the partner to come in to be tested.  Ideally, this would be information that would help that couple make a decision or at least be aware, when the baby is born, the baby will be tested.  The baby may have sickle disease if each of those parents has sickle cell trait.


Dr. Linda Austin:  Dr. Jackson, we’ve really covered some of the genetic issues.  Let’s pause there and do another podcast on what, really, is the course of the illness in a baby who is born with sickle cell anemia.  Thank you so much.


Dr. Sherron Jackson:  Thank you.


If you have any questions about the services or programs offered at the Medical University of South Carolina or if you would like to schedule an appointment with one of our physicians, please call MUSC Health Connection:  (843) 792-1414.


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