Sickle Cell disease Flashcards
What is sickle cell disease?
When red blood cells are more easily destroyed because they are in a sickle shape
this can cause anaemia
What is the primary haemoglobin type affected in sickle cell disease?
HbA - 2 alpha + 2 beta peptide chains
What causes sickle cell disease?
A mutation in the beta globin gene causing the beta chains to be misshapen
What type of disease is sickle cell?
Autosomal recessive
Carriers don’t notice symptoms unless they are exposed to extreme conditions
What is one positive of sickle cell disease?
It decreases the severity of malaria
How is sickle cell disease tested for?
on the newborn screening heel prick test at 5 days of age.
What is HbS?
Sickle haemoglobin
- 2 alpha chains
- 2 beta (sickle) chains (Both chains have to be mutated)
What extreme conditions can cause sickle carriers to experience symptoms?
High altitude
Dehydration
What happens when oxygen is bound to haemoglobin?
The HbS carries oxygen around perfectly well, theres no problems until the oxygen is unbound
What happens when theres no oxygen bound to the HbS?
The haemoglobin changes its shape and binds to other proteins causing the red blood cell to become a present shape = sickling
How are RBCs destroyed?
By intravascular haemolysis
Where does free haemoglobin after haemolysis go?
Binds to haptoglobin.
Low haptoglobin is a sign of sickle cell disease
What does low haptoglobin show?
Intravascular haemolysis is occurring
What are signs/complications of sickle cell disease?
Dactylitis (sickle cells getting blocked in small blood vessels in the digits)
Pain crisis
Avacsular necrosis
Increased bone formation (increased bone marrow to try and increase more RBCs)
Hepatomegaly (liver also tries to make RBCs)
Splenic infarcts
Strokes
Haematuria
Gallstones
What investigations can be done for sickle cell disease?
Blood smear - shows sickle cells
Protein electrophoresis - identifies HbS
