Alpha Thalassemia: Clinical Pathology

by Carlo Raj, MD

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    00:00 Alpha-thalassemia, now, pay attention here.

    00:03 If it's Asian, you see this right here.

    00:06 It's the two dash lines in parenthesis that represents two alleles missing from the same parent.

    00:14 So, this is the cis pattern, look at your population.

    00:18 Southeast Asia, given Malaysia, Singapore, and so forth.

    00:20 If it's African, now, what this means in parenthesis is that one dash represents one allele from each parent missing, for combination of two.

    00:31 So, this is trans pattern and this will be the African.

    00:34 Both of these, they're missing two alleles, it has to be which one? Which alpha-thalassemia? Trait, good. Let's take a look at lab studies.

    00:43 Well, this is obviously going to be microcytic, so MCV will be decreased.

    00:47 By definition, hemoglobin decreased.

    00:50 Hematocrit, hematocrit usually falls hemoglobin, rule of thumb, so that will be decreased.

    00:55 As far as your RBC count, it will be normal, I'll just call it variable.

    01:00 Variable RBC count. Your red blood cell distribution width, you do not find uniformity, so that will be increased. HbH, how many alleles should you -- for you, on your exam, how many alleles are you missing in order for you to have HbH? Three, keep it simple. Understand, those of you that wish to go onto hemotology, it's a lot more detailed. Even normal individuals like you and I will have, without a three allele deletion, could have circulating HbH.

    01:31 So, if you wanna read about it, by all means, please do so, but to be efficient with your studying, three alleles, HbH, what are you aggregating? You're precipitating beta or gamma? Very good. Beta, beta, betaglobins. Excellent.

    01:48 And what about your iron studies? It will be normal because why? We're not touching the heme. It's a globin that's been infected.

    01:56 HbH disease, signs and symptoms of anemia. It's pretty severe.

    02:00 Remember, at best to be intermediate but you're looking for severe anemia, anemia missing three.

    02:04 The chronic hemolysis, where does RBC go for its grave or its death? The spleen. So, you're gonna release unconjugated biliburin, which means what? Indirect bilirubin, which means it will be a lipid soluble Here it comes, it's coming out of the blood vessels, into the skin, you have jaundice and what kind of gal stone, please? Cholelithiasis.

    02:26 Good, bilirubin, pigment stones. Don't choose cholesterol, do you -- that makes no sense.

    02:32 Cholesterols, as granted, are the most common but my goodness, when you're hemolysis, you see this. It has to be pigment stones or bilirubin.

    02:41 What color is that? What do you mean by pigment? Pigment.

    02:43 Black. It will be black. Very dark, very dark.

    02:47 This is an HbH disease with chronic, chronic, chronic, type of hemolysis.

    02:51 What's it termed? Extramedullary hematopoiesis. What does that mean? The normal recruitment or development of your RBC in adult, once again, go -- if you want, go, grow -- look at this as being your anatomical sequence.

    03:05 Sternum, ribs, humerus, if that helps you. Now, it's a bone marrow.

    03:09 That's as an adult, but chronically, you see frontal bossing, that's what you see here in this picture here.

    03:15 Portrution because the suture lines are pushing the frontal bone forward.

    03:19 Hepatosplenomegaly as well, all due to extramedullary If it's four that you're missing, four alleles that are missing, no chance of birth, no chance of life, intrauterine, and death is occurring.

    03:33 Take a look at that huge stomach there, what that means is that your child intrauterine death because of high output anasarca hydrops fetalis.

    03:42 Unfortunate, four alleles that are missing.

    03:45 Hepatosplenomegaly, cancer causes death, prenatal period.

    03:51 Alpha-thalassemia, I wanna show you here how to enterpret your patterns once again, really quick. On your left, take a look at normal.

    03:59 I want you to divide this and after explaining this, you'll see how easy this is.

    04:03 Mother, father, a total of four. Two strips, one strip is mother, another strip is father.

    04:11 Take a look at the top, alpha/alpha, alpha/alpha, four. Normal.

    04:15 If it's your African, trans.

    04:18 Look at the mother, there's one dash, and by mother, I'm just being arbitrary here.

    04:24 So, I'll just call that first strip the mother, one allele missing.

    04:29 I'll call the second strip there in the middle as being father, one allele missing.

    04:33 What pattern is this? Trans. You've heard of trans before.

    04:37 Believe it or not, you really have and you've heard it with all-trans retinoic acid.

    04:41 Remember that? All-trans retinoic acid is something that you'd use for membro acute myelogenous, acute myelogenous leukemia type 3.

    04:48 So, you've heard of trans before, let me just put it into context.

    04:51 And then the last patient there, patient B, you'll notice that it is two dash lines, meaning two alleles missing from the same, that's your cis pattern.

    05:03 And that, of course, will be your Asian. That's it. Let's move on.

    About the Lecture

    The lecture Alpha Thalassemia: Clinical Pathology by Carlo Raj, MD is from the course Microcytic Anemia – Red Blood Cell Pathology (RBC).

    Included Quiz Questions

    1. Hemoglobin H disease
    2. Alpha thalassemia trait (trans pattern)
    3. Hemoglobin Barts disease
    4. Silent carrier of alpha thalassemia
    5. Alpha thalassemia trait (cis pattern)
    1. Hemoglobin Barts
    2. Hemoglobin H
    3. Hemoglobin F
    4. Hemoglobin A2
    5. Hemoglobin S

    Author of lecture Alpha Thalassemia: Clinical Pathology

     Carlo Raj, MD

    Carlo Raj, MD

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