EMZYMOPATHIES AND MEMBRANOPATHIES

Question 1

What is the structure of the red cell?

Answer 1

A biconcave discallowing flexibility and efficient navigation in narrow capillaries.

Question 2

Why is red cell metabolism important?

Answer 2

It generates ATP (via anaerobic glycolysis) to maintain shape volume

Question 3

What are the key enzymes in red cell metabolism?

Answer 3

Glucose-6-phosphate dehydrogenase (G6PD) and pyruvate kinase.

Question 4

What is the role of G6PD in red cells?

Answer 4

It reduces NADP to NADPH which keeps glutathione in its reduced form to prevent oxidative injury.

Question 5

What is the most common cause of red cell membrane disorders?

Answer 5

Defects in cytoskeletal proteins like spectrin ankyrin

Question 6

What is the pathophysiology of spherocytosis?

Answer 6

Deficiency or structural defects in spectrin reduce surface-to-volume ratio creating less flexible spherical red cells prone to extravascular hemolysis.

Question 7

What is the pathophysiology of elliptocytosis?

Answer 7

Mutations in spectrin disrupt the cytoskeletal lattice resulting in elliptical-shaped red cells prone to hemolysis.

Question 8

What are clinical features of red cell membrane disorders?

Answer 8

Anemia jaundice

Question 9

How is hereditary spherocytosis diagnosed?

Answer 9

Reduced fluorescence in eosin-5-maleimide staining spectrin deficiency on electrophoresis

Question 10

What is the treatment for hereditary spherocytosis?

Answer 10

Folic acid supplementation splenectomy for severe cases

Question 11

What triggers hemolysis in G6PD deficiency?

Answer 11

Oxidative stress from infections drugs (e.g.

Question 12

What are the clinical syndromes in G6PD deficiency?

Answer 12

Acute hemolytic anemia neonatal jaundice

Question 13

What are Heinz bodies?

Answer 13

Aggregates of denatured hemoglobin visible with special stains

Question 14

What are key findings in G6PD deficiency during a hemolytic episode?

Answer 14

Anemia bite cells

Question 15

How is G6PD deficiency diagnosed?

Answer 15

Enzyme assay although levels may be falsely normal during a hemolytic crisis; repeat testing later is advised.

Question 16

What is the inheritance pattern of G6PD deficiency?

Answer 16

X-linked recessive.

Question 17

What is pyruvate kinase (PK) deficiency?

Answer 17

An autosomal recessive enzyme defect causing impaired ATP production and rigid red cells leading to extravascular hemolysis.

Question 18

What are clinical features of PK deficiency?

Answer 18

Milder anemia than G6PD deficiency splenomegaly

Question 19

What is the treatment for PK deficiency?

Answer 19

Folic acid supplementation transfusions if needed

Question 20

What complications are common in red cell enzymopathies?

Answer 20

Iron overload gallstones

Question 21

What is unconjugated hyperbilirubinemia?

Answer 21

An increase in unconjugated bilirubin due to excessive hemolysis leading to jaundice.

Question 22

What are gallstones in hemolytic anemia composed of?

Answer 22

Pigmented bilirubin stones due to chronic hemolysis.

Question 23

What is the conclusion about membrane and enzyme disorders?

Answer 23

These inheritable intracorpuscular defects cause hemolytic anemia with membrane defects causing extravascular hemolysis and enzyme defects causing mixed hemolysis.