Sickle Cell Disease

Question 1

What is Sickle Cell disease?

Answer 1

This is an autosomal recessive
disease that results from the
substitution of glutamic acid
(hydrophilic) for valine
(hydrophobic) at position 6 of the
beta-globin chain.
The disorder results from a point
mutation (GAG changing to GTG)
on chromosome 11.

Question 2

Pathophysiology of SCD

Answer 2

Deoxygenated HbS molecules are
insoluble and polymerize. This
increases viscosity

Flexibility of the cells is decreased
and they become rigid and take up
their characteristic sickle
appearance

Question 3

Precipitating factors of SCD

Answer 3

 Hypoxia
 Dehydration
 Cold
 Acidosis
 Infection and fever
 Living at high altitude

Question 4

Clinical features/ crises

Answer 4

 Sequestration crisis
 Hyper-hemolytic crisis
 Aplastic crisis
 Vaso-occlusive crisis (chest pain syndrome, dactylitis, hand and foot syndrome, acute abdomen, priapism, avascular necrosis, stroke, retinal hemorrhages)

Question 5

Investigations

Answer 5

♂️HB electrophoresis ( gold standard)
♂️ Blood investigations (FBC, PBS- Howell Jolly bodies/Target cells, sickling test, blood culture, arterial blood gases)
♂️Imaging (chest X ray, x-ray of skull- hair on end appearance, MRI, CT, Transcranial Doppler, Echo, spirometry, abdominal U/S)