Enzymopathies Flashcards
1
Q
What enzymopathy is the most common cause of hereditary Chronic non-spherocytic haemolytic anaemia (CNSHA)? Bonus Q what other enzymopathies causes this?
A
-Pyruvate kinase deficiency //Also G6PD deficiency and Glucose 6-phosphate isomerase
2
Q
-Outline the clinical features of Pyruvate kinase deficiency
A
- Extravascular haemolysis
- Jaundice
- Gallstones frequent
3
Q
Describe the treatment for pyruvate kinase deficiency
A
- Nothing specific
- Transfusions for anaemia (thought anaemia is tolerated well in these patients)
- Splenectomy
- Folate
- iron chelation
4
Q
Name 4 enzymopathies
A
- G6PD deficiency
- Pyruvate kinase deficiency
- Glucose 6-phosphate isomerase deficiency
- Hexokinase deficiency
5
Q
Outline pathophysiology of G6PD deficiency
A
- Deficiency of G6PD affects the pentose phosphate pathway
- Decreased generation of NADPH results
- decreased NADPH causes a decrease in reduced glutathione
- Glutathione is crucial for protecting the red cell from oxidative stress - As a result of the decreased reduced glutathione, the red cell is susceptible to oxidant stress and lysing, leading to haemolytic anaemia.
6
Q
Describe the clinical features of G6PD deficiency
A
- usually asymptomatic
- Increased tendency to experience acute haemolytic anaemia
- Neonatal jaundice
- CNSHA
7
Q
Why does G6PD deficiency only affect red cells?
A
- Because mature red cells are unable to synthesize new proteins and therefore new enzymes.
- As red cells ‘age’ their levels of G6PD decrease
8
Q
How does G6PD cause haemolysis?
A
- In absence of G6PD, more oxidative damage occurs to haemoglobin
- Hb is oxidised irreversibly into methaemoglobn
- Precipitates as ‘Heinz bodies’ that attach to the cell membrane
- Red cell membrane proteins also become oxidised, causing cell rigidity.
- Cell rigidity causes lysis
9
Q
What drugs must be avoided in G6PD deficiency? (3 examples?)
A
- Dapsone
- Methylene blue
- Nitrofurantoin
- Primaquine
