HbA2 is a minor adult hemoglobin comprising about 2-3% of total hemoglobin in normal adults. What is its subunit composition?

• A α2β2
• B α2γ2
• C β4
• D α2δ2 ✓

Explanation

HbA2 has the composition α2δ2. HbA (α2β2) is the major adult hemoglobin (~97%), and HbF (α2γ2) is the fetal hemoglobin. HbH (β4) is an abnormal tetramer seen in alpha-thalassemia. Knowing the chain composition of each hemoglobin type is essential for interpreting hemoglobin electrophoresis patterns.

Reference: DeGruchy's Clinical Haematology in Medical Practice, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.