Sickle Cell Anemia: Etiology

00:01 Let’s take a look at the all important sickle cell anemia and how your patient is going to present.

00:08 To begin with, let’s get straight into the detail.

00:11 I want you to take a look at what’s bold in here.

00:14 You’ll find glutamic acid which is then being replaced by valine at position 6.

00:23 That will be the most important substitution that you want to be responsible for.

00:27 And in fact, you actually screen for this on your beta globin and you call this E6V.

00:33 And what E6V means, meaning to say like -- Nowadays, you can actually genetically screen for a patient that you would suspect as having sickle cell anemia by doing a glutamic acid E6 position for valine.

00:50 This gives HbS.

00:53 For every HbS that you then acquire then you end up having either a heterozygous or a homozygous type of pattern.

01:03 Obviously, whenever you have a homozygous type of disease, that is far more worse than a heterozygous.

01:09 Are we clear? It’s an autosomal recessive inheritance which means that you can only pick up one.

01:15 If you pick up one, you end up having what? Sickle cell trait.

01:19 That’s heterozygous.

01:21 If you pick up both, if homozygous then that will be sickle cell disease.

01:26 Make sure that you are quite familiar with the terminology and the language.

01:30 What you’re seeing here at the bottom, ladies and gentlemen, is a very important amino acid and a test in which the first one, on your left, is showing you hemoglobin A on your beta globin.

01:41 And you notice that the 6 position, well, there is my glutamic acid.

01:46 Do you see the 6 position in red? I would also know GAG from genetics.

01:52 The one on the right, you find that the glutamic acid is being replaced by valine.

01:57 At what position? Six.

01:59 This is GTG.

02:01 So the A is being replaced by T, the glutamic acid replaced by valine at the 6 position.

02:08 What did you form in the process? On the right, on the beta globin, take a look, you formed your hemoglobin S.

02:16 Move on.