Electrospray Ionization Mass Spectrometric Analysis of the Globin Chains in Hemoglobin Heterozygotes Can Detect the Variants HbC, D, and E

Abstract

methodological issues concerning design and conduct of test-outcome studies. Comprehensive discussions of this complex and important area are available (1-4 ), and in the textbook Evidence-Based Laboratory Medicine the chapter on assessment of outcomes is especially relevant (5 ).Our purpose is to highlight the importance of moving from diagnostic accuracy studies to evaluations of the effects of test results on clinical decision-making and subsequent health outcomes. In agreement with other investigators (1-5 ), we support efforts to increasing the use of outcome studies to enhance the effectiveness of healthcare policy and decision-making.

Strategy for Identification by Mass Spectrometry of a New Human Hemoglobin Variant with Two Mutations inCisin the β-Globin Chain: Hb S-Clichy [β6(A3)Glu→Val; β8(A5)Lys→Thr]

“…Thus, in the case of a Hb S heterozygous carrier with clinical symptoms similar to sickle cell anemia, a careful study including a combination of IEF, CE-LC, RP-LC and MS analyses are required. However, limitations of mass difference measurements by ESI-MS instruments must also be considered (28)(29)(30)(31)(32). From a practical point of view, the Q-STAR XL instrument (Applied Biosystems) is a quadrupole mass spectrometer (33,34), and it can be used for tandem MS/MS, but also in ESI mode for measuring globin chains masses.…”

Clinical Applications

“…Currently used methods to detect hemoglobinopathies include ion exchange chromatography (IEX) and isoelectric focusing (IEF) both of which are time consuming and generally exhibit poor specificity when unusual post-translational modifications occur. Many articles have been published on the use of MS and MS/MS for the determination of hemoglobin (Hb) variants via molecular weight determinations on intact -globin chains [214][215][216] . These techniques suffer from situations where the mutation involves a zero (nominal) mass change such as Lys↔Gln or Leu↔Ileu.…”

A combined top‐down and bottom‐up MS approach for the characterization of hemoglobin variants in Rhesus monkeys

“…For instance, the theoretical monoisotopic peak for the α2-Hb variant is 15088.902, which is not visible in the deconvoluted spectrum shown in Figure 5, even though the corresponding m/z at 795.16 is present in the original spectrum. Therefore, many researchers rely on the most abundant ion instead of the monoisotopic ion and treat this as if it was average mass ( Figure 6), which may attribute to the reported achievable mass accuracies that have been controversially discussed [25,26]. Lacking currently better alternatives, we also used the most abundant ion in the monoisotopic clusters and treated it as if it was average mass, even though we are fully aware that these masses should and do differ as shown in Figure 6.…”