This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Medicine
HbH is characterized by - 
Select and explain. 
A. Deletion of three alpha chain genes, B. Deletion of three alpha chains and one beta chain genes, C. Deletion of two alpha and two beta chain genes, D. Deletion of four alpha chain genes
A: Deletion of three alpha chain genes
Answer: A: Deletion of three alpha chain genes 
Explanation: <p>Deletion of 3 alpha chain genes produces Hb H which is a beta globin chain tetramer & markedly impaired alpha chain synthesis.</p><p>Reference : Harsh mohan textbook of pathology sixth edition pg no 321.</p>