Hb A₂-Calderdale [δ2(NA2)His→Asn; HBD: c.7C>A] and Misdiagnosis of Type 2 Diabetes Mellitus Due to Interference with Hb A_1c When Using Cation Exchange High Performance Liquid Chromatography: A Case Report

Abstract

The Hb A₂-Calderdale variant [δ2(NA2)His→Asn, HBD: c.7C>A] was described as a novel variant in 2014. However, a high performance liquid chromatography (HPLC) peak was never identified indicating that this fraction could be ‘hiding’ somewhere else in the chromatogram. In this case report, we present evidence that the physiochemical properties of Hb A₂-Calderdale resemble those of Hb A_1c, resulting in a coelution in variant mode on the Tosoh G8 but not the Tosoh G11. This coelution results in an overestimation of Hb A_1c and can potentially cause misdiagnosis of type 2 diabetes mellitus (T2DM).

Keywords:

• δ-Globin gene
• Hb A_1c
• Hb A₂-Calderdale
• high performance liquid chromatography (HPLC)

Acknowledgements

The authors thank Anette Glibstrup (Medical Laboratory Technologist, Rigshospitalet, Copenhagen, Denmark) and Charlotte Amtoft (Product Specialist, Sysmex Nordic Aps, Copenhagen, Denmark) for excellent technical assistance, and Stefan Stender, PhD, MD (Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark), for helpful comments on an earlier version of this short communication.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.