Hb F-La Grange or alpha 2 gamma 2 101(G3)Glu----Lys; 75Ile; 136Gly: a high oxygen affinity fetal hemoglobin variant observed in a Caucasian newborn.

The identification of a newly discovered gamma-chain variant is reported. This abnormal fetal hemoglobin is characterized by a Glu----Lys substitution at position 101(G3) of its gamma chain and was observed in a Caucasian baby girl. Because glutamic acid residue in position gamma 101 is involved in the alpha 1-gamma 2 chain contact, its replacement by a lysine residue results in changes in physicochemical and functional properties. The variant readily forms hybrid hemoglobins at room temperature, is mildly unstable at higher temperature, and has an increased oxygen affinity with a somewhat lower heme-heme interaction.