Functional properties of the newly observed Gγ-chain fetal hemoglobin variant Hb F-Monserrato-Sassari (HBG2:c.280T > C) or [Gγ93 (F9) Cys → Arg]

► HbF-Monserrato-Sassari is a newly discovered abnormal human fetal hemoglobin. ► It is characterized by the Arg for Cys replacement at position 93 of the Gγ globin. ► It shows increased oxygen affinity, slightly decreased Bohr effect and cooperativity. ► Cys γ93 has a key role for subunit cooperativity in the T → R transition of the HbF. ► Substitutions at this position may stabilize the high affinity R-state of the Hb and endanger nitric oxide transport.