Sickle Cell Disease Flashcards
What is sickle cell disease (SCD)?
A heterogeneous group of autosomal recessive haematological disorders characterised by distortion of haemoglobin into a sickle shape.
SCD is primarily caused by a mutation in the beta-globin gene.
What mutation causes sickle cell disease?
A point mutation in the beta-globin gene changing adenine to thymine, altering the codon from valine to glutamate.
This mutation leads to the production of haemoglobin S (HbS).
What is the result of HbS exposure to low oxygen saturation?
It causes polymerisation of HbS, making red blood cells (RBCs) rigid and adopting a sickle shape.
This rigidity can lead to blockages in blood vessels.
What is sickle cell anaemia?
A homozygous form of sickle cell disease (HbSS disease) where both beta-globin genes have the mutation.
It is the most severe form of sickle cell disease.
At what age do symptoms of sickle cell anaemia typically present?
Symptoms typically present in infants who are 3-6 months old.
This is when fetal haemoglobin (HbF) begins to turn into adult haemoglobin (HbA).
What is chronic haemolytic anaemia?
A condition where abnormal breakdown of RBCs occurs faster than they can be produced.
This condition is often seen in sickle cell anaemia.
What is jaundice in the context of sickle cell disease?
Yellowing of the skin and sclera due to bilirubin, a byproduct of RBC death.
It is commonly associated with the increased haemolytic rate.
What triggers an increase in the haemolytic rate during sickle cell crisis?
Sickle cells sticking together and blocking capillaries.
This blockage can lead to vaso-occlusive crises.
What are common complications during a sickle cell crisis?
- Sequestration (organ engorgement with blood)
- Organ damage (e.g., spleen infarction)
- Acute chest syndrome
Spleen infarction can lead to autosplenectomy.
What is sequestration in sickle cell disease?
A condition where organs become engorged with blood, most commonly in the liver and spleen.
This can cause significant organ damage.
What is acute chest syndrome?
A life-threatening complication caused by sickling in the lungs during a sickle cell crisis.
It can lead to severe respiratory distress.
Fill in the blank: Sickle cell anaemia presents initially as _______ due to the faster breakdown of RBCs.
chronic haemolytic anaemia
This condition is exacerbated by the transition from HbF to HbA.
True or False: Sickle cell disease is only caused by environmental factors.
False
Sickle cell disease is primarily caused by genetic mutations.
What is the haemoglobin trait of severe sickle cell disease that presents early in life and resembles acute crises?
HbS HbS
What is the haemoglobin trait of sickle cell disease that presents later in life and is less severe?
HbS HbA
