BL4 Flashcards
Do sickle B thalassemias (+ and 0) have small, normal, or large RBC size
small
-All of the other sickle cell disease have normal sized RBCs
Which 2 sickle cell diseases are the most clinically severe?
Sickle cell anemia (HbSS)
and
Sickle-βothalassemia (Hb Sβothalassemia)
What are you expected to find on a smear sickle cell disease?
○ sickle forms
○ schistocytes (“broken”, irregular cells)
○ polychromasia (big, fat, blue-colored cells representing reticulocytes)
○ anisocytosis (variation in size of RBCs)
○ poikilocytosis (variation in shape of RBCs).
In Pt’s w/ sickle cell disease without a spleen, what distinct structure are you expected to find on a smear sickle cell disease?
Howell-Jolly bodies (purple dots) within RBCs
-one of spleens job is to make sure RBCs are able to get rid of their nucleus and fragments
Sickle cell trait
different from Sickle cell disease.
one NORMAL gene and one sickle gene.
○ Normal gene → normal β globin chains/normal quantity → protects against sickle cell disease
Normal adults have an alpha2beta2 Hb structure, Describe the Hb gene mutations of: Sickle cell anemia: Sickle beta-thalassemia: Sickle cell disease: Sickle cell trait:
Sickle cell anemia:
- both beta genes have sickle cell mutation
- (HbS S)
Sickle beta-thalassemia:
-one beta gene is sickle, and one is Bo (major) or B+ (minor) - (HbS B+/o)
Sickle cell disease:
- one beta gene is sickle, one is a C (beta globin variant)
- ( HbS C)
Sickle cell trait:
- one normal gene, one sickle gene
- Hb AS
What is the leading cause of death in acute complications of sickle cell disease?
Vascular leak: endothelial retraction in response to injury, leaving intercellular gaps
Aplastic crisis
○ Anything that leads to a sudden drop in reticulocyte count
ie: hemoglobin levels.
How does ParvovirusB19 affect aplastic crisis?
Parvovirus B19 → infects RBC precursors → arresting development into mature RBCs →aplastic crisis
○ Usually transient
3 approaches to treating sickle cell disease?
- Bone marrow transplantation:
- Hydroxyurea Therapy
- Transfusion therapy
What does the Sickle cell heal prick detect?
• Determines amt of Hb in blood spot.
○ If too little normal Hb → perform another test
○ If 2nd test abnormal → notify parents → refer to specialist
alpha like genes for Hb are found on which chromosome?
Beta like genes?
· Chromosome 16: “α-like” genes ( zeta and α)
· Chromosome 11: “β-like” genes (e, β,γ, δ)
Describe what Thalassemia is w/ regards to Hb
• Thalassemia:
○ Condition w/ underproduction of either α or β Hb chain due to variety of mutation that results in poor or absent function of globin gene
aka “ you have too many of 1 chain!”
α-Thalassemia
what is it?
what is it due to?
○ α-globin chain is underproduced
○ Due to absence of 1/m of the four genes which control production
β-Thalassemia
what is it?
what is it due to?
○ β-globin chain is underproduced
○ Due to point mutation in β-globin gene → dysfunctional gene
Would you expect high or low MCV for thalassemia? Why?
Low
structurally abnormal Hb, low [ ] Hb in RBCs
In terms of genes, differentiate between β-thal minor, intermedia, major (cooleys)
β-thal minor: 1 normal β gene, 1 abnormal β gene - heterozygous
intermedia: 2 mildly abnormal β genes
major (cooleys): 2 severely abnormal β genes
