has causal or contributing genetic variation Abnormal Hemoglobin Hemoglobin D Request inclusion in the HPO, below "Abnormal Hemoglobin". An abnormal hemoglobin caused by various point mutations within the HBB gene. This form of hemoglobin prevents red blood cells from carrying oxygen effectively. There are at least 8 different types of hemoglobin D. HbD Few but definitions not freely available Hb D Haemoglobin D HBB, SER9TYR HBB, GLU121GLN HBB, GLY16ARG HBB, ASN19LYS HBB, GLU22GLN HBB, GLU22VAL HBB, THR87LYS HBB, GLU121ALA