Characterization of Hb Calvino (HBB: c.406G > A): A New Silent β-Globin Gene Variant Found in Coexistence with α-Thalassemia in a Family of African Origin

Abstract We report a new silent β-globin gene variant found in a family from Angola living in the north eastern Italian city of Ferrara. The probands, two young sisters, presented with hematological parameters compatible with a β-thalassemia (β-thal) minor but with normal Hb A2 levels and normal hemoglobin (Hb) separation on high performance liquid chromatography (HPLC). Molecular analyses revealed a homozygosity for the common -α3.7 (rightward) deletion and heterozygosity for a novel transition (GCT > ACT) at codon 135 of the β-globin gene, leading to an Ala → Thr single amino acid substitution that was inherited from the healthy father