Hemoglobinopathies Flashcards Preview

DPPT Unit 2 > Hemoglobinopathies > Flashcards

Flashcards in Hemoglobinopathies Deck (11):
1

On what chromosome is the alpha globin gene cluster located?

Chromosome 16

2

On what chromosome is the beta globin gene cluster located

Chromosome 11

3

What is the amino acid substitution that causes sickle cell disease?

Glutamic acid (hydrophilic) changed to valine (hydrophobic)

4

What is the amino acid substitution that causes HbC (mild sickle cell disease)?

Glutamic acid changed to lysine

5

How is sickle cell disease diagnosed?

(1) Hb electrophoresis
(2) Molecular detection of HbS and HbC mutant alleles

6

What are four forms of therapy for sickle cell disease?

(1) Preventative - penicillin prophylaxis, vaccination, avoidance of hypoxia
(2) Hydroxyurea - induce HbF production
(3) Chronic RBC transfusion
(4) Analgesics for pain

7

What does α thalassemia result from?

Gene deletion on chromosome 16

8

What does β thalassemia result from?

Point mutation on chromosome 11

9

What are the consequences of varying numbers of α gene deletions?

(1) αα/α- - silent carrier
(2) αα/-- or α-/α- - α-thalassemia trait (mild anemia, microcytosis)
(3) α-/-- - HbH disease (β4, moderate to severe hemolytic anemia)
(4) --/-- - Hydrops fetalis, homozygous α thalassemia (Hb Bart's: γ4)

10

What is the clinical presentation of β thalassemia?

(1) Microcytic anemia
(2) Target cells on histology from central blebbing due to low Hb and RBC deflation
(3) Crewcut appearance on x-ray and chipmunk facies from extramedullary hematopoiesis

11

How are mutant alleles classified in β thalassemia?

β+ - partially functional β globin
β0 - no functional β globin made