Haematology - Sickle Cell Anemia

Question 1

History

Answer 1

James B. Herrick (1861 -1954); discovered: 1910, first molecular disease described in humans

Question 2

Pathophysiology

Answer 2

2 normal alpha chains & 2 variable beta chains; results from mutation at codon 6 of beta chain (beta^s); bc deoxyhaemoglobin S is insoluble, HbS polymerises to form tac to ids that distort RBCs; autosomal recessive (HbSS sickle cell, HbAS sickle trait)

Question 3

Epidemiology

Answer 3

beta^S gene distribution matches that of endemic Plasmodium falciparum malaria; up to 25% sub-Saharan Africans and 10% Caribbeans carry HbS gene; ~300000 affected births worldwide; Bantu, Benin, Senegal, Asia