Could you tell me the symptoms of hemoglobin d, and any other useful information?

Usually none: Patients with hemoglobin d disease (both copies of the beta-hemoglobin gene carry the mutation) usually have mild anemia and no symptoms. If someone has both hemoglobin d and the mutation for sickle cell disease, they can have health problems. For an excellent overview of hemoglobin d, see: http://www.Stjude.Org/stjude/v/index.Jsp?Vgnextoid=30f0db6324d6f110vgnvcm1000001e0215acrcrd.