Reliability of hemoglobin A2 value as measured by the Premier Resolution system for screening of β-thalassemia carriers.

Abstract

Accurate quantification of hemoglobin (Hb) A2 is vital for diagnosing β-thalassemia carriers. This study aimed to assess the precision and diagnostic utility of HbA2 measurements using the new high-performance liquid chromatography (HPLC) method, Premier Resolution, in comparison to capillary electrophoresis (CE). We analyzed 418 samples, previously identified as A2A by CE, using Premier Resolution-HPLC. We compared the results, established correlations, and determined an optimal HbA2 cutoff value for β-thalassemia screening. Additionally, we prospectively evaluated the chosen cutoff value in 632 samples. Mutations in the β- and α-globin genes were identified using polymerase chain reaction (PCR) techniques and DNA sequencing. HbA2 levels were consistently higher with Premier Resolution, yet there was a significant correlation with CE in all samples (bias,-0.33; r, 0.991), β-thalassemia (bias,-0.27; r, 0.927), and non-β-thalassemia carriers (bias,-0.36; r, 0.928). An HbA2 cutoff value of≥4.0 % for β-thalassemia screening achieved 100 % sensitivity and 99.6 % specificity. Further validation yielded sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 97.3 , 99.8, 97.3, 99.8, and 99.7 %, respectively. We also identified a rare β-Hb variant, Hb La Desirade [HBB:c.389C>T], associated with β-thalassemia and co-inherited with a single α-globin gene. The Premier Resolution HPLC is a reliable and accurate method for routine β-thalassemia carrier screening, aligning with existing CE methods.