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Glucose-6-Phosphate Dehydrogenase Glucose-6-Phosphate Dehydrogenase

Glucose-6-Phosphate Dehydrogenase - PowerPoint Presentation

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Uploaded On 2017-05-20

Glucose-6-Phosphate Dehydrogenase - PPT Presentation

Deficiency G6PDD The glycolytic pathway is the main source of energy ATP The hexose monophosphate shunt pathway provides the main source of reduced nicotinamide adenine ID: 550337

cells hemolytic enzyme hemolysis hemolytic cells hemolysis enzyme g6pd anemia oxidant red chronic blood hemoglobin rbcs cell deficiency acute drugs jaundice fava

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Presentation Transcript

Slide1

Glucose-6-Phosphate Dehydrogenase Deficiency(G6PDD)Slide2

The glycolytic pathway is the main source of energy (ATP)

The

hexose monophosphate ‘shunt’ pathway provides the main source of reduced nicotinamide adenine dinucleotide phosphate (NADPH), which maintains reduced glutathione (GSH) and protects haemoglobin and the membrane proteins against oxidant damage. Slide3

Genetics1. Sex-linked recessive mode of inheritance by a gene located on the X chromosome (similar to hemophilia).

2.

Disease is fully expressed in hemizygous males and homozygous females.,there is an advantage of resistance to falciparum

malaria in heterozygous females.Slide4

Pathogenesis- Red

cell integrity impaired, especially on exposure to oxidant drugs, oxidant response to infection and chemicals.

Oxidation of hemoglobin and of sulfhydryl groups in the membrane.- Oxidized hemoglobin precipitates to form Heinz bodies which are plucked out of the red cell leading to hemolysis and

bite cell

and

blister cell

morphology.Slide5

WHO Classification of G6PD VariantsSlide6

Clinical FeaturesEpisodes of hemolysis

may be produced by:

• Drugs. • Fava bean (broad bean): ingestion or exposure to pollen from the bean’s flower (favism

)

Infection.

symptoms develop 24

48 hr after a patient has ingested a substance that has oxidant properties

,

The degree of hemolysis varies with( the inciting agent, the amount ingested, and the severity of the enzyme deficiency).

The

enzyme is abundant and more stable in younger RBCs. The associated

reticulocytosis

produces a compensated hemolytic process. Slide7

PRECIPITATING FACTORSAntimalarials: primaquine, quinine,

chloroquine

Antibiotics - nitrofuantoin, furazolidine, cotrimoxazole, Nalidixic acid, Chloramphenicol,Others :

Vitamin K – large doses

Naphthalene (moth balls)

Benzene, Methylene blue

Probenecid

Acetyl salicylic acid (aspirin)

Fava beans

Septicemia and viral hepatitis

Diabetic ketoacidosisSlide8

1. Drug-induced hemolysisa. Typically in African-Americans but also in Mediterranean types

c. Acute self-limiting hemolytic anemia with

hemoglobinuriad. Heinz bodies in circulating red cellse. Blister cells, fragmented cellsf.

Reticulocytosis

g. Hemoglobin normal between episodes.Slide9

2. Favism

This results from oxidative products derived from 2

glycosidic compounds, vicine and convicine, which are hydrolyzed to divicine and

isouramil

, ultimately producing

hydrogen peroxide

and other reactive oxygen products.

Acute life-threatening hemolysis, often leading to acute renal failure, associated with Mediterranean.

Blood transfusion is required.Slide10

3. Neonatal jaundiceInfants may present with pallor, jaundice (can be severe and produce kernicterus)and dark urine. When a pregnant woman ingests oxidant drugs, they may be transmitted to her G6PD-deficient fetus, and hemolytic anemia and jaundice may be apparent at birth.

Occasionally exposure to naphthalene (mothballs), aniline dye, marking ink, or a drug. Slide11

Chronic nonspherocytic hemolytic anemia

Occurs mainly with sporadic

inheritance it variable but can be severe with transfusion dependence and intense neonatal presentation(NNJ)

Persons with G6PD B

(Mediterranean) enzyme deficiency occasionally have chronic hemolysis, and the hemolytic process may worsen after ingestion of oxidant drugs.

Splenectomy

is of little value in these types of chronic hemolysis.Slide12

LABORATORY FINDINGS.-Blood

film:RBCs

reveal Heinz bodies (precipitated hemoglobin. Because cells containing these inclusions are rapidly removed from the circulation, they are not seen after the first 3–4 days of illness. The blood film reveals a few fragmented and polychromatophilic cells (bluish, large RBCs), representing reticulocytosis

(5

15%).Slide13

DIAGNOSISThe diagnosis depends on direct or indirect demonstration of reduced G6PD activity in RBCs.

By direct measurement

, enzyme activity in affected persons is ≤10% of normal. Immediately after a hemolytic episode, reticulocytes and young RBCs predominate. These young cells have significantly higher enzyme activity than do older cells. Testing may therefore have to be deferred for a few weeks before a diagnostically low level of enzyme can be shown. Slide14

Satisfactory screening tests are based on - decoloration of methylene blue,

- reduction

of methemoglobin- fluorescence of NADPH

G6PD variants also can be detected by

electrophoretic

analysis

.Slide15

Management1. Avoidance of agents that are deleterious in G6PD deficiency.

2.

Education of families and patients in recognition of food prohibition (fava beans), drug avoidance, heightened vigilance during infection and the symptoms and signs of hemolytic crisis (orange/dark urine, lethargy, fatigue, jaundice).3. Indication for transfusion of packed red blood cell in children presenting with acute hemolytic anemia:a. Hemoglobin (

Hb

) level below 7 g/dl

b. Persistent

hemoglobinuria

and

Hb

below 9 g/dl.

4

.

Chronic

nonspherocytic

hemolytic anemia (NSHA):

In patients with severe chronic anemia: transfuse red blood cells to maintain

Hb

level (8

10 g/dl) and iron chelation when needed.