Hb A2-Konz [δ50(D1)Ser → Thr; HBD: c.151T > A]: a new δ chain hemoglobin variant characterized by mass spectrometry and high performance liquid chromatography.

We report a new slow-moving δ chain hemoglobin (Hb) variant, named Hb A2-Konz [δ50(D1)Ser → Thr; HBD: c.151T > A]. It was detected during simultaneous measurement of Hb A1C and Hb A2 by high resolution cation exchange high performance liquid chromatography (HPLC) using a PolyCATA column. Hb A2-Konz comprised 0.8% of total Hb. This new variant was identified by peptide mapping using nanoliquid chromatography electrospray ionization-tandem mass spectrometry (nanoLC-ESI-MS/MS) as a serine to threonine substitution at δ50(D1), indicating that the variant was due to a single base change at codon 51 (TCT > ACT) of the δ-globin gene. The new mutant is clinically silent but could lead to a misdiagnosis of β-thalassemia (β-thal) based on the level of Hb A2.