A 2-year-old child from a Mediterranean family has severe anemia with a hemoglobin of 4 g/dL, massive hepatosplenomegaly, and skeletal deformities. Peripheral smear shows target cells and nucleated RBCs. The finding on Hb electrophoresis that confirms beta-thalassemia major is:

• A Hb S predominant with absent Hb A
• B Elevated Hb A2 only, Hb A normal
• C Hb Barts predominant with absent Hb A
• D Absent Hb A, elevated Hb F and elevated Hb A2 ✓

Explanation

In beta-thalassemia major (beta0/beta0 or beta0/beta+ severe), beta-globin chains are absent or severely reduced, so Hb A (alpha2-beta2) is absent or minimal. Compensatory gamma-chain synthesis results in elevated Hb F (alpha2-gamma2), and excess alpha chains bind delta chains, elevating Hb A2 above 3.5%. Hb S pattern is sickle cell disease; elevated Hb A2 alone characterizes beta-thalassemia trait; Hb Barts predominance is alpha-thalassemia hydrops fetalis.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.