Abstract
Hemoglobinopathies, including sickle cell disease (SCD) and thalassemia's, are the most common monogenic diseases globally, affecting an estimated 7% of the world's population. Each year, 300,000–500,000 infants are born,globlaly with severe hemoglobinopathies, with about 83% of cases being sickle cell disorders and 17% thalassemia's. SCD resulting from a single point mutation in the β-globin gene leads to a severe debilitating disease assosicated with elevated mortality. Conventional diagnostic techniques such as high-performance liquid chromatography (HPLC), capillary electrophoresis provide accurate hemoglobin electrophoresis but are often costly, time-intensive, and require centralized laboratory facilities with skilled personnel. HPLC results typically become available within 1 to 7 days for routine testing at most clinical laboratories in the USA today.In this study, we present the results from a novel, real-time, point-of-care (POC) assay for quantification of hemoglobin variants associated with SCD and beta thalassemia. We evaluated its performance against the standard laboratory method, HPLC, for the first time in North America. Additionally, we assessed the usability of a next-generation microfluidic cartridge intended for operation by untrained users.
Methods: The Gazelle platform uses miniaturized electrophoresis to separate and identify hemoglobin variants. It provides results—including Hb type, percentage composition, and interpretative statements for conditions such as SCD (including variants), sickle cell trait, and beta thalassemia—in approximately 8–10 minutes, using fingerstick, heel-prick, or venous blood samples.Through an IRB approved clinical study, patient samples from Loma Linda University School of Medicine were tested using both Gazelle and HPLC for comparative analysis of quantitation accuracy. A simplified cartridge (Gen 2) was also developed, incorporating microfluidics to streamline sample preparation and reduce procedural complexity. Usability testing was conducted with 14 lay users who completed the test after reviewing brief training materials (instructional video or IFU). Outcomes were assessed through a structured usability questionnaire and task completion metrics.
Results:The study is ongoing; to date, 9 patient samples have been analyzed for concordance .Participants were aged 12-25 years and included both males and females. Gazelle produced quantitative results for key variants, including Hb S,C,F and Hb A, in under 10 minutes. Correlation with HPLC for these variants demonstrated a Pearson coefficient of 0.977 for Hb S and 0.998 for Hb A. The real time novel testing platform demonstrated 100% sensitivity and specificity in distinguishing normal from disease, and disease from trait, as well as 100% sensitivity and 100% specificity in distinguishing trait from disease. Addiitonally quantification of Fetal and Hgb A2 showed high accuracy with the mean absolute error (MAPE) of 3.58 and 4.6% respectively. Usability assessments showed that all 14 users, regardless of technical background, were able to prepare and run the test with no errors after a single review of the training material in an ambluatory clinic setting.
Conclusion:Even in high-resource countries real-time electrophoresis is hampered by a lack of standardized point-of-care quantification. The simplified Gazelle test demonstrates high accuracy, excellent usability, and rapid turnaround time for SCD and related hemoglobinopathies. Clinical applications in ambulatory and acute care setting makes this platform especially useful to inform clinicians of real time electrophoresis results that potentially could be used for diagnosis, dose adjustment,calculating volumes for red cell transfusions (especially erythocytophoresis), monitor progress of cell/gene therapy. Use of this technology in underserved regions of North America to quantify/classify disease/trait in patients, that have not underwent new born screening could be vital. With the ongoing assesment in additional participants (target of 500 samples) in North America , results of high accuracy akin to larger testing in Asia and Africa ( reported earlier ) are expected. These preliminary results support Gazelle as a viable tool for expanding access to early diagnosis and population screening efforts in North America.
