Male1: There is a disease called sickle-cell anemia?
Male2: Yes, that is actually a disease, another genetic disorder where the hemoglobin is affected. This is somewhat different in what we have just discussed where instead of having--where there is a very specific mutation in that hemoglobin that changes the chemical are activities of this very central molecule in the blood and becasue of that, all kinds of problem ensue. This disease again, the genes come from some place and in this particular situation, the gene originates in Africa, in essentially Central Africa, and then from there has moved to the Mediterranean basin to some degree. There is some level of sickle-cell present in areas like for instance Saudi Arabia, and then obviously, there is sickle-cell present here in the United States and in a number of other countries, where African genes had moved over time. So it is a fairly common problem amongst African-American or originated from the Caribbean Islands, we have the African ancestry. The overall country with Thalassemia where probably the numbers are measured in hundreds to a few thousand here in the United States. There are probably about a hundred thousand patients with sickle-cell disease here in the United States and many people carry the trait obviously. This is a--you may have heard about the so-called newborn screening. A drop of blood is obtained from the newborn to check for a number of genetic disorders, and one of the genetic disorder that is actually checked for is the sickle-cell disease and the reason why we want to know about sickle-cell disease at birth rather than a few months afterwards is because one of the major concerns early in life with sickle-cell disease is infections and all babies with sickle-cell anemia are detected at birth and they are essentially started on anti-biotics, a simple penicillin to prevent infection, very early in life in the first couple of years.
Male1: What kind of infections are they prone to?
Male2: There are bacterial infections that are typically pneumococcuses which is one of the bacterias that is involved in giving people pneumonia, but in this particular group of patients, since they cannot handle it well because of spleen problems that ensue in this particular disease becomes what we call sepsis and infection of the blood, where they can be potentially lethal and very rapidly and there are very good studies that have shown that the use of penicillin during the first five years of life essentially almost completely prevents that problem.
Male1: Do we get infections involving the joints sometimes?
Male2: They do, although it is not the most common problem in this particular—
Male1: More of an arthritic type?
Male2: Yes, what they tend to do is they actually have bone problems, but their bone problems are more related with what is so called sickle-cell crisis, and the sickle-cell crisis shows itself in different ways, for instance, the infant often has what is called a handfoot--a disease because there are the bones in the hand and the feet, they swell up and they are very painful and obviously, a little baby who cannot communicate well will be very cranky or very irritable without a true reason and occasionally, you see the swelling in the hands and the feet.
Male1: So these patients should be immunized againts pneumococcal disease?
Male2: Absolutely. The advent--they have been immunized againts pneumococcal disease with something called the pneumococcal vaccine which was not conjugated and that was given at age 2. Now, there is a pneumococcal vaccine that can be actually given much earlier and it started at about age two months with a complete immunization by the age of one year. At the moment, it is not yet clear whether or not this immunization so early will eventually eliminate the need of pulling this patient on prophylactic penicillin, there is no study available at this time, and since the prophylaxis with penicillin is essentially free of complication, the moment all patients with sickle-cell disease should be on penicillin.
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