Hb Santander [β34(B16)Val→Asp (GTC→GAC)]: A New Unstable Variant Found as a De Novo Mutation in a Spanish Patient

Abstract

A careful analysis of hematological data obtained from patients with mild hemolytic anemia may suggest the presence of an unstable hemoglobin (Hb) variant. This diagnosis needs to be confirmed by appropriate laboratory procedures (1,2). This was the case for a 22-year-old Spanish male patient presenting with jaundice and suffering from hemolytic crises during infections. In this patient, we found a new unstable Hb variant, in which the valine residue at position 34 of the b-globin chain was replaced by an aspartic acid. This variant has been characterized at the gene level by DNA sequencing, revealing a GTC!GAC mutation at codon 34 of the b-globin gene. It was named Hb Santander after the city where the proband lives. Hematological data were obtained with a Coulter GENS (Coulter Electronics, Ltd, Luton, UK). Hb A2 was measured by anion exchange chromatography (3) and Hb F according to the method described by Betke et al. (4). Hemoglobin was studied by electrophoresis on cellulose acetate at pH 8.6, electrophoresis on citrate agar gel (pH 6.0), isoelectrofocusing (IEF) on polyacrylamide gel (pH 5.5‐8.5) and by ion exchange high performance liquid chromatography (HPLC) using a TSK-CM-2-SW column (Tosohaas, Montgomeryville, PA, USA) and a linear gradient from 100% buffer A to 100% buffer B