Direct Detection of Oxy Asymmetrical Hemoglobin Hybrids in Blood Samples

Hb Chicago is a newly discovered hemoglobin variant which was present in a Black newborn baby and her father. The leucine residue at α136, which normally participates in the contact with the heme group, is replaced by a methionine residue. The two heterozygotes were clinically well with normal hematological data. Isolation of the α^x and α^A chains by reverse phase high performance liquid chromatography and hydrolysis of these chains with dilute formic acid at 110°C for 24 hours, followed by separation of the resulting peptides by reverse phase high performance liquid chromatography, greatly facilitated the final identification of the abnormality. The baby and both parents had a-G_γ-G_γ-globin gene arrangement on one chromosome (normal:-G_γ-A_γ which explains the high a G^γ values in the Hb F of these three persons.