Adult Hemoglobin Hemoglobin A Haemoglobin A Haemoglobin A1 HbA The most common and normal adult human hemoglobin tetramer, comprising over 97% of the total red blood cell hemoglobin and consisting of two alpha chains and two beta chains. Few but definitions not specific enough MESH:D006441 alpha2beta2 Hb A Request inclusion into NCIT below "Hemoglobin"/"Normal Hemoglobin". Suggest update to description in MESH. Hemoglobin A1 Adult Haemoglobin Normal Hemoglobin