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Background HbA1c is used in the diagnosis and monitoring of diabetes mellitus (DM). Interference from hemoglobin variants is a well-described phenomenon, particularly with HPLC-based methods. While immunoassays may generate more reliable HbA1c results in the presence of some variants, these methods are susceptible to negative interference from high concentrations of HbF. We report a case where an accurate HbA1c result could not be obtained by any available method due to the presence of a compound hemoglobinopathy. Methods HbA1c was measured by HPLC, immunoassay, and capillary electrophoresis. Hemoglobinopathy investigation consisted of a CBC, hemoglobin fractionation by HPLC and electrophoresis, and molecular analysis. Results HbA1c analysis by HPLC and capillary electrophoresis gave no result. Analysis by immunoassay yielded HbA1c results of 5.9% (Siemens DCA 2000 +) and 5.1% (Roche Integra), which were inconsistent with other markers of glycemic control. Hemoglobinopathy investigation showed HbC with the hereditary persistence of fetal hemoglobin-2 Ghana deletion. Conclusion Reliable HbA1c results may be unobtainable in the presence of some hemoglobinopathies. HPLC and capillary electrophoresis alerted the laboratory to the presence of an unusual hemoglobinopathy. Immunoassays generated falsely low results without warning, which could lead to missed diagnoses and under treatment of patients with DM. [ABSTRACT FROM AUTHOR]

Background A novel double heterozygosity for the α chain variant Hb Q India and β chain variant Hb S is described. Hb S is prevalent in the central part of India while Hb Q India in its heterozygous state is found mainly in Sindhi families. Methods Identification of both the variants, Hb S and Hb Q India, was done based on chromatograms of HPLC and capillary zone electrophoresis (CE). Confirmation of variants was done by PCR based amplification refractory mutation system (ARMS) technique. Results Both HPLC and CE confirmed the presence of Hb S. HPLC showed a pointed narrow peak of Hb Q India at retention time of 4.55 min while it is eluted in Hb D zone on CE. A hybrid variant of these α and β globin chains was eluted in Hb C window and Hb C zone on HPLC and CE respectively. Molecular studies using ARMS technique confirmed these findings. Both the cases showed positive sickling test and presented with mild anemia. Conclusion This is a unique 2 index cases for compound heterozygosity of Hb S with Hb Q India. [ABSTRACT FROM AUTHOR]