Identification of a new hemoglobin variant Hb Liuzhou [HBA1:C.182A→G] by MALDI-TOF mass spectrometry during HbA1c measurement.

Structural hemoglobin (Hb) variant is generally caused by a point mutation in the globin gene that produces one amino acid substitution. Here, we describe a new α-chain variant found during HbA1c measurement. HbA1c procedures based on both ion-exchange high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) techniques failed to identify its presence. In contrast, MALDI-TOF mass spectrometry (MS) revealed the existence of a variant α-chain with a mass of 15155 Da. In addition, the Hb variant interfered with HbA1c determined by Bio-Rad D100. DNA sequencing confirmed the occurrence of a new heterozygous mutation [HBA1:C.182A→G] at codon 60, resulting in a coding change from lysine to arginine. We named it Hb Liuzhou for thde birthplace of the patient. This case exemplified that MALDI-TOF mass spectrometry can serve as the method of choice to identify and quantify the Hb variant.