A New Silent β Chain Variant: Hb Hounslow [β80(EF4)Asn→Tyr]

We report a new neutral hemoglobin (Hb) variant, found, during neonatal screening, in a child originating from Afghanistan. This variant was revealed by cation exchange and reversed phase high performance liquid chromatography (HPLC), but was silent in electrophoretic methods except for globin chain electrophoresis in the presence of urea and Triton X-100. The structural modification was determined by protein structure studies and the substitution established by tandem mass spectrometry (MS/MS). The mutation, located near to the 2,3-diphosphoglycerate (2,3-DPG) binding site, was without any hematological consequences. The pitfalls presented by the presence of neutral Hb variants as modulator factors of the main hemoglobinopathies is discussed.