G6PD Deficiency: Biochemistry of G6PD

by Carlo Raj, MD

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    00:00 Don’t let them do that to you.

    00:01 Okay, so let’s take a look at our G6PD and a couple of things that are important for us.

    00:06 So here, I want you to move to the left and I want you to identify glucose here.

    00:11 And then this is the glycolytic pathway.

    00:14 We’re going to branch off the glycolytic pathway and there’s my rate-limiting enzyme, G6PD, glucose-6-phosphate dehydrogenase.

    00:22 What are you going to form? Look, you took NADP and you formed NADPH.

    00:28 Where do you actually require that NADPH for? You’re going to take oxidized glutathione and you will reduce it.

    00:35 Remember in biochemistry, if you reduce something, what does that mean to you? Oh, yeah, you create the active form.

    00:41 So here’s my GSH, that is the reduced form of glutathione.

    00:45 Ladies and gentlemen, that is what protects us.

    00:49 That is what protects the RBC.

    00:52 Against whom? Free radicals.

    00:55 What does a free radical mean to you? Oxygen and company.

    00:59 So for example, do you remember superoxides? Do you remember hydrogen peroxide? Which one are we seeing here? That’s hydrogen peroxide.

    01:09 That’s a free radical.

    01:10 But where did it come from? Take a look at that box.

    01:13 Infections most commonly.

    01:16 Doesn’t that then produce free radicals? Of course, drugs such as – Remember antimalarials.

    01:22 I told you if you’re about to go to a tropical country and you’re taking antimalarials for months and months and months.

    01:29 You’re introducing free radicals.

    01:31 What was the name of that bean in the Mediterranean that they consume in their diet? The fava bean.

    01:36 So all of these would then be introducing a free radical, that GSH, which is the glutathione.

    01:43 We’ll take the free radical, hydrogen peroxide and make it into water, which is completely benign and it’s a neutralizer, isn’t it? So imagine, please, that your patient doesn’t have G6PD.

    01:59 You're not going to produce NADPH.

    02:01 You don’t activate glutathione.

    02:02 Uh-oh, free radical damage.

    02:05 What is it going to cause damage to? That hemoglobin.

    02:08 What do you call that hemoglobin now? Heinz body.

    02:12 Who are you going to attract? Phagocytic cell.

    02:15 What do you produce? Bite cells.

    02:17 What was that other thing that I told you? Not only do we have hemolytic anemia, but you also have susceptibility to infection.

    02:24 What kind of organisms? Catalase-positive.

    02:29 Everything that we just talked about here is what you’re seeing.

    02:31 It’s all lined up, X-linked recessive.

    02:35 And then the last little part that I wish to add is the part on the top, very right, and you find that if you don’t have G6PD deficiency, you end up forming your Heinz bodies.

    02:45 In terms of its hemolysis, it could either intravascular or it could be extravascular, is that clear? Take a look at that arrow, where it says G6PD deficiency, that’s important.

    02:55 Intra or extravascular, both instances occur.

    03:03 What we’re looking at here in this picture is your Heinz body.

    03:08 How does this occur? Free radical exposure, fava beans, infections, drugs.

    03:14 What are you going to find next? You’re going to find bite cells.

    About the Lecture

    The lecture G6PD Deficiency: Biochemistry of G6PD by Carlo Raj, MD is from the course Hemolytic Anemia – Red Blood Cell Pathology (RBC).

    Included Quiz Questions

    1. Reduced glutathione (GSH)
    2. Oxidized glutathione (GSSG)
    3. Myeloperoxidase
    4. Nicotinamide adenine dinucleotide phosphate oxidase
    5. Hydrogen peroxide
    1. Oxidized glutathione to reduced glutathione
    2. Reduced glutathione to oxidized glutathione
    3. Oxygen to superoxide
    4. Adenosine diphosphate (ADP) to adenosine monophosphate (AMP)
    5. Glucose 6 phosphate to 6 phosphogluconate
    1. Catalase positive
    2. Catalase negative
    3. Urease positive
    4. Coagulase negative
    5. Coagulase positive

    Author of lecture G6PD Deficiency: Biochemistry of G6PD

     Carlo Raj, MD

    Carlo Raj, MD

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