Hb Calgary (HBB: c.194G>T): A Highly Unstable Hemoglobin Variant with a β-Thalassemia Major Phenotype

We describe two unrelated patients, both heterozygous for an unstable hemoglobin (Hb) variant named Hb Calgary (HBB: c.194G>T) that causes severe hemolytic anemia and dyserythorpoietic, resulting in transfusion dependence and iron overload. The molecular pathogenesis is a missense variation on the β-globin gene, presumed to lead to an unstable Hb. The phenotype of Hb Calgary is particularly severe presenting as transfusion-dependent anemia in early infancy, precluding phenotypic diagnosis and highlighting the importance of early genetic testing in order to make an accurate diagnosis.

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

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 -α(3.7) (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.