<prompt> HbH is characterized by:Deletion of three alpha chain genesDeletion of three alpha chains and one beta chain genesDeletion of two alpha and two beta chain genesDeletion of four alpha chain genes  <response>: Ans. A. Deletion of three alpha chain genesAlpha-ThalassemiaSilent carrier state1 gene deletion-aaa thalassemia trait2 gene deletion-a-aHbH disease3 gene deletion---aHydrops fetalis4 gene deletion--- 