Hemoglobin A and A2, one high and one low, can be caused by a variety of reasons, and the common causes include α-pearl protein production disorder anemia, severe iron deficiency anemia, and iron granulocytic anemia. 1. α-pearl protein production disorder anemia: it can be divided into severe, intermediate, light, and stationary types. Generally, light and stationary types are asymptomatic, while severe and intermediate types may show symptoms such as anemia, jaundice, liver and spleen enlargement, and so on. 2. Severe iron-deficiency anemia: Mildly, it can be manifested as pale skin, dizziness, fatigue, etc. If it is severe, it can cause a high hemoglobin a and a2 and a low hemoglobin. 3. Iron granulocytic anemia: can be caused by genetic factors, drugs such as isoniazid, chemotherapy drugs and hematopoietic system diseases such as leukemia, etc., can be manifested as pale skin, fatigue, active palpitations and other symptoms, but also can cause hemoglobin a and a2 a high and a low. Hemoglobin a and a2 a high and a low, can also be seen in other diseases, need to be combined with laboratory tests to confirm the diagnosis, it is recommended that the patient to the hospital in time to avoid delaying the condition.