Two Complex Associations of an HBD Mutation and a Rare α Hemoglobinopathy

Abstract

We present two case reports in which an HBD mutation is present with a rare α hemoglobinopathy that substantially complicates the associated phenotype. In the first case, a new δ-globin variant, Hb A₂-Pierre-Bénite [δ83(EF7)Gly→Arg; HBD: c.250G>C] is associated with Hb Groene Hart [α119(H2)Pro→Ser (α1); HBA1: c.358C>T], an α-thalassemic variant. In the second case, a δ⁺-thalassemic variant, δ4(A1)Thr→Ile; HBD: c.14C>T, is associated with a newly described deletion of the hypersensitive site 40 (HS-40) region on the α-globin gene cluster. In both patients, a δ-globin mutation was suspected because of an abnormally low Hb A₂ level, whereas the α hemoglobinopathy was sought to explain the slight microcytosis and hypochromia presented by the probands.

• HBD mutation
• α-Thalassemia (α-thal)
• Hb Groene Hart
• Hypersensitive site 40 (HS-40) deletion