Incidental finding of rare hemoglobin: hemoglobin Bari in northeast Spain

Cation exchange high-performance liquid chromatography (HPLC) is one of the techniques available for determining glycated hemoglobin (HbA_1c) and also the method of choice for structural hemoglobinopathies screening. The objective of this case is to show how in a routine HbA_1c test it is possible to incidentally find a hemoglobinopathy.

In a routine blood analysis, an abnormal value for the hemoglobin A2 (HbA₂) was obtained during the study of HbA_1c with HPLC on the ADAMS™ A1c HA-8180T. After suspecting it could be due to the presence of a hemoglobinopathy, the study of possible variants was expanded using electrophoresis and HPLC on the Hydrasys and Variant II analysers, respectively. Since it could not be identified by these conventional methods, a genetic study was also carried out using Sanger sequencing. The patient presented a low HbA₂ (1.3 %) and a 24.9 % variant with a retention time of 1.95 min, compatible with alpha-globin chain variant. In the genetic study, the pathogenic variant c.138C>G was detected in the HbA gene in heterozygosis, which resulted in the expression of the structural hemoglobinopathy known as hemoglobin Bari.

The initial screening for structural hemoglobinopathies allows its identification or suspicion especially when it was performed with HbA_1c analysis, requiring subsequent confirmation and diagnosis by other techniques.