Sickle Cell Disease

Question 1

Mutation leading to SCA

Answer 1

point substitution mutation at 6th position in B globin chain causes hydrophilic glutamatic acid to be replaced with hydrophobic valine. Hydrophobic interactions with alanine and leucine cause shape change.

Question 2

Sickle Cell on blood films

Answer 2

Sickle shaped cells, hypochromia (less colour, flatter), reticulocytes, microcytic, Howell-jolly bodies, mcv

Question 3

Pathophysiology

Answer 3

Haemolytic anaemia,
vaso-occlusive crises / chronic tissue damage ( blocking and adhesion - ishaemia and infarction) of
bone - dactylitis, avascular necrosis, osteomyelitis.
lungs - acute chest syndrome , pulmonary hypertension.
eyes - retinopathy
stroke
enlarged spleen (sequestration)
sepsis
gastrointestinal - gall stones
urogenital - renal dysfunction , priapism

Question 4

Triggers for Sickle Cell crises

Answer 4

Cold weather - vasoconstriction more blockage. Dehydration , higher HbS conc : more polymerisation. 
Infections 
Stress
Exertion 
Hypoxia

Question 5

Home treatment for Sickle Cell crises

Answer 5

Painkillers
Heating pads
Hydration

Question 6

Treatment

Answer 6

Hydroxycarbamide - increase HbF
Antibiotics
Folates
Painkillers - morphine 
Blood transfusions
Gene therapy

Question 7

Chain constitution of haemoglobins

Answer 7

HbA - 2 a , 2 b
HbA2 - 2 a , 2 d
HbF - 2b - 2y

Question 8

Symptoms

Answer 8

Acute pain 
tiredness
fever
vision loss
swelling 
headaches