Hemoglobin Variant Hemoglobin G-Philadelphia Sufficient Hemoglobin G Philadelphia Hb G-Phil SCDO:1000689 HbG Phil LNC:LP16433-2 Hb G-Philadelphia Hemoglobin G Philadelphia (HbG Phil) is a structural variant of the hemoglobin molecule that involves the alpha chain rather than the beta chain. It has a frequency of about 1 in 5,000 African Americans, but has been reported in other ethnic groups in the Mediterranean region as well, HbG Phil itself has no clinical consequences. The only finding of clinical interest is the mild microcytosis. While this molecule has no clinical consequences, the presence helps to distinguish HbG from HbD that shares its electrophoretic migration on HPLC and gel electrophoresis and which does have consequences when it occurs with sickle trait.