Question

Why don't infants suffer from sickle cell anemia?

(Need an in-depth answer that focuses on the biology, including amino acids and blood cells)

Answer 1

Basics :-
Hemoglobin -
• Iron containing protein molecule found in RBC which transport oxygen in blood.
• There are several different types of globin chains, named alpha, beta, delta, and gamma.

Normal hemoglobin types include:

(1) Hemoglobin A (Hb A): makes up about 95%-98% of hemoglobin found in adults. It contains two alpha (α) chains and two beta (β) protein chains.

(2) Hemoglobin F (HbF): Main hemoglobin during fetal life and newborns and then replaced by HbA.
• It formed by two alpha and two gamma chains.
• It disappears after 7 months (approx.) of birth.

Abnormal hemoglobin -
HbS/ deoxy Sickle hemoglobin: Formed in sickle cell disease.
• Abnormal beta chains are formed.
• Polymerization of Hbs causes suckling of RBCs.

Now -
Why don't infants suffer from sickle cell anemia?
• Because infants have high concentration of Hemoglobin F.
Role of HbF -
• It inhibits the polymerization of Hbs and inhibits sickling of RBCs.

Extra -
Hydroxyurea, an inducer of HbF, has been approved for the treatment of patients with moderate and severe sickle cell disease.