Unreliable estimation of HbA due to the presence of Camperdown haemoglobin [beta 104 (G6) Arg --> Ser]

Aims: To suggest the possible unreliability of HbA 1c determination in presence of haemoglobin variants during routine metabolic evaluation. Methods: We present a case of Camperdown haemoglobin, accidentally detected in a middle-aged Italian man during routine metabolic evaluation for newly diagnosed diabetes. The haemoglobin variant has been identified by exchange high performance liquid chromatography (CE-HPLC) (VARIANT™ HbA 1c Program, Bio-Rad Laboratories, Hercules, CA, USA), and characterized at molecular level by direct sequencing. Results: A 56-year-old male of Northern Italian origin, presented to our centre for a Type 2 diabetes mellitus of recent diagnosis. HbA 1c determination was routinely determinated. The patient's chromatogram showed an inappropriate peak of 38.5% in the HbA 1c position suggestive for the presence of abnormal haemoglobin. Further evaluation identified an abnormal haemoglobin peak even higher (49.5%) eluting at 1.34 minutes in P2-window. Molecular characterization of the mutation showed a nucleotide replacement, AGG → AGC at codon 104, causing the amino acid replacement Arg → Ser at position 104 (G6) that give rise to Hb Camperdown. Conclusions: Haemoglobinopathies can lead to inaccurate glycated haemoglobin level determination. In patients carrying haemoglobin variants, the different methods for determinations of glycated haemoglobin could result in different errors, showing either higher or lower values than expected.