This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
HbH is associated with: 
Select and explain. 
A. Deletion of 3 alpha genes, B. Deletion of 4 alpha genes, C. Deletion of 3 beta genes, D. Deletion of 4 beta genes
A: Deletion of 3 alpha genes
Answer: A: Deletion of 3 alpha genes 
Explanation: HbH Disease is associated with deletion of 3 out of 4 alpha globin genes. Ref: Robbins pathologic basis of disease 6th edn/page 619.