G6PD Deficiency: Biochemistry of G6PD

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.