Mass spectrometry based characterization of Hb Beckman variant in a falsely elevated HbA(1c) sample

Das, Rajdeep and Muralidharan, Monita and Mitra, Gopa and Bhat, Vijay and Mathew, Boby and Pal, Debnath and Ross, Cecil and Mandal, Amit Kumar (2015) Mass spectrometry based characterization of Hb Beckman variant in a falsely elevated HbA(1c) sample. In: ANALYTICAL BIOCHEMISTRY, 489 . pp. 53-58.

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Abstract

Glycated hemoglobin (HbA(1c)) is a `gold standard' biomarker for assessing the glycemic index of an individual. HbA(1c) is formed due to nonenzymatic glycosylation at N-terminal valine residue of the P-globin chain. Cation exchange based high performance liquid chromatography (CE HPLC) is mostly used to quantify HbA(1c), in blood sample. A few genetic variants of hemoglobin and post-translationally modified variants of hemoglobin interfere with CE HPLC-based quantification,. resulting in its false positive estimation. Using mass spectrometry, we analyzed a blood sample with abnormally high HbA(1c) (52.1%) in the CE HPLC method. The observed HbA(1c) did not corroborate the blood glucose level of the patient. A mass spectrometry based bottom up proteomics approach, intact globin chain mass analysis, and chemical modification of the proteolytic peptides identified the presence of Hb Beckman, a genetic variant of hemoglobin, in the experimental sample. A similar surface area to charge ratio between HbA(1c) and Hb Beckman might have resulted in the coelution of the variant with HbA(1c) in CE HPLC. Therefore, in the screening of diabetes mellitus through the estimation of HbA(1c), it is important to look for genetic variants of hemoglobin in samples that show abnormally high glycemic index, and HbA(1c) must be estimated using an alternative method. (C) 2015 Elsevier Inc. All rights reserved.

Item Type:	Journal Article
Publication:	ANALYTICAL BIOCHEMISTRY
Publisher:	ACADEMIC PRESS INC ELSEVIER SCIENCE
Additional Information:	Copy right for this article belongs to the ACADEMIC PRESS INC ELSEVIER SCIENCE, 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA
Keywords:	Cation exchange HPLC; HbA(1c); Hb Beckman; Hemoglobin variant; Mass spectrometry; Glycemic index
Department/Centre:	Division of Interdisciplinary Sciences > Supercomputer Education & Research Centre
Date Deposited:	05 Nov 2015 06:37
Last Modified:	05 Nov 2015 06:37
URI:	http://eprints.iisc.ac.in/id/eprint/52668

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