Application of electrospray triple quadrupole mass spectrometry in assessing thalassemia in a population.

INTRODUCTION: Thalassemia is widely prevalent in Asian countries and the Middle East region of the world. While the prevalence of α thal is around 5-20% in the population, the incidence of ß thal is around 3-4%. The available data on thalassemia in Indians is based on chromatographic or electrophoretic techniques. The present study demonstrates the utility of mass spectrometry in detecting thalassemia in a small, healthy population from Tiptur, Karnataka. MATERIALS AND METHODS: The study included a population of 315 individuals, spanning both children and adults, with ages ranging from 4 to 76 years. EDTA whole blood was collected after obtaining their written consent. The intensities of various globin chains were measured using a triple quadrupole mass spectrometer. The ratio of the peak areas of globin chains (α/ß, δ/ß (%)) served as biomarkers to detect thalassemia. Thirty random samples of α thalassemia were analyzed using GapPCR. RESULTS: The prevalence of a thal is 21.65% (68/314) based on α/ß (< =0.8) and the prevalence of ß thal is 3.8% (12/314) based on δ/ß (%) (> =11.0). GapPCR detected three heteromutants of α deletion, one mutation in the HBA1 gene, and one a triplication (16.7%, 5/30). One sample was excluded from the analysis due to the presence of a variant. CONCLUSION: The utility of mass spectrometry for screening thalassemia in a population is demonstrated. The higher occurrence of α-thalassemia in the studied population underscores the importance of screening for thalassemia in regions with reportedly high prevalence rates.

Retrospective study on the distribution of hemoglobinopathies in Karnataka-A laboratory experience.

AIMS: The importance of screening for hemoglobinopathies is well-documented in India. However, information on the distribution of hemoglobinopathies in Karnataka is lacking. The present study focuses on determining the spectrum of hemoglobinopathies for various districts of Karnataka. MATERIALS AND METHODS AND RESULTS: A retrospective analysis of samples registered for hemoglobinopathies for a period of 5 years (2017-2021) was carried out. A total of 17066 records registered only from the Karnataka region, were anonymized and retrieved. The data included gender, age, district, and results of the tests. The results were based on complete blood count, peripheral smear, and capillary electrophoresis (CE) pattern. The data were revalidated by pathologists, and the unambiguous data were analyzed for the study. One-fourth of the records (25%) showed abnormal hematological parameters. The number of female records (66%) was twice that of males and both genders showed higher distribution of thalassemia, followed by variants and double heterozygotes (DH). Several cases of thalassemia major were identified below the age of 17 years. The majority of thalassemia cases were ß thal and 93% of them were ß thal trait. Among the variants, HbS was more prevalent than HbE. Among the districts, Hassan had a 35.2% thal, Mysuru had a 7.2% variant, and Chitradurga had a 5.5% DH. Thalassemia, variants, and DH were distributed across several districts of Karnataka to various levels. CONCLUSION: The comprehensive retrospective analysis of the spectrum of hemoglobinopathies in various districts of Karnataka serves as evidence to carry out a prospective study on population screening where the incidence of thalassemia and structural variants is high.

A Qualitative Method to Detect Paraproteins from Serum Using Ultra Performance Liquid Chromatography Electrospray Triple Quadrupole Mass Spectrometry.

BACKGROUND: Mass spectrometry-based techniques are increasingly reported in the literature for identifying paraproteins due to their improved specificity and sensitivity. The present study demonstrates the capability of ultra performance liquid chromatography (UPLC) electrospray ionization triple quadrupole mass spectrometry for the qualitative analysis of paraproteins. METHODS: Paraproteins from patient serum (n = 40) were immunopurified using agarose beads coated with camelid antibodies that are specific for various subtypes of immunoglobulins (Igs; G, A, M, and light chains κ, λ). The extracted Igs are reduced to separate light chains from heavy chains in solution. The reduced sample was subjected to UPLC and mass measured using electrospray ionization-mass spectrometry. The mass spectral peaks at specific retention times were deconvoluted after clean-up to obtain the mass of light chains. The interpretation of liquid chromatography peaks and LC-MS data was validated by comparing them with immunofixation electrophoresis (IFE) results. RESULTS: The interpretation from the chromatographic pattern had a 92.5% (37/40) agreement when compared with mass information. The correlation of mass spectrometry data to IFE was 90% (36/40). The high mass of light chains (>25 kDa) was suggestive of glycosylation. Patient sera positive for IgGκ on IFE (n = 15) were analyzed for the interference of tAbs. The mass of Daratumumab observed in a sample was confirmed by the treating physician. A biclonal of same isotype (IgGκ) was identified. CONCLUSIONS: The feasibility of using liquid chromatography triple quadrupole mass spectrometry for the identification of the subtype of paraproteins has been demonstrated. The method's applicability to screen for interference from tAbs and identification of biclonals of the same isotype has been highlighted.