P-002: multispectral imaging for microchip electrophoresis enables point-of-care newborn hemoglobin variant screening

Purpose: Epidemiological modeling shows that universal screening of sickle cell disease (SCD) could save the lives of up to 9.8 million newborns with SCD by 2050. The World Health Organization (WHO) estimates that early diagnosis of SCD coupled with intervention programs would prevent 70% of existing SCD mortality. SCD newborn screening (NBS) performed in centralized laboratories has dramatically reduced SCD mortality in resource-rich countries. SCD NBS requires sensitive detection of low levels of certain hemoglobin (Hb) variants (i.e., sickle Hb, HbS) in the context of high levels of expression of other Hb variants (i.e., fetal Hb, HbF). The current centralized tests used for NBS for SCD are high performance liquid chromatography (HPLC) and isoelectric focusing. However, in SSA and central India, where >90% of annual SCD births occur, NBS programs have not been implemented universally due to the cost and logistical burden of laboratory diagnostic tests. As a result, there is a need for affordable, portable, easy-to-use and accurate point-of-care (POC) tests to facilitate decentralized Hb testing in low-resource settings for enabling nationwide NBS. Materials and methods: We have leveraged the WHO listed Hb electrophoresis test and developed a POC electrophoresis microchip, Gazelle-Multispectral (Fig. 1A) that enables sensitive detection and identification of Hb types under both white and violet (410nm) light illumination. We hypothesized that the high absorbance of Hb at 410 nm wavelength would enhance the limit of detection and allow detection of low concentration Hb types o enable SCD screening in newborns. To test this hypothesis, we have conducted clinical testing over 441 subjects under the age of 6 months including 265 newborns with Hb variants including HbA (normal hemoglobin), HbF, HbS, and HbC (hemoglobin C variant) at Korle Bu Teaching Hospital, under IRB-approved protocol. Results: Separated Hb variants are imaged under both white light illumination (Fig. 1B) and 410 nm illumination (Fig. 1C). The acquired data under white light illumination demonstrates the natural red color of hemoglobin and is used for test validation(Fig. 1B). The acquired data under 410 nm is used for sensitive and accurate identification and quantification of Hb variants (Fig. 1C&D), and to automatically generate report for result interpretation (Fig. 1E). Following the Standards for Reporting of Diagnostic Accuracy Studies guideline, 365 out of 441 tests were recognized as ‘Valid’. Gazelle-Multispectral determined Hb variant levels demonstrated high association with Person Correlation Coefficients of 0.97, 0.97, 0.93, and 0.95 for Hb A, Hb F, HbS, and HbC compared to HPLC. Gazelle-multispectral demonstrated accuracy of 96.8% in subjects of 0-3 days, and 96.9% in newborns. (Table 1). Conclusion: Gazelle-Multispectral imaging enables affordable and rapid identification of common Hb variants in newborns at the point-of-need. The internally integrated data analysis algorithm automatically reports Hb type identification and quantification results in an objective and easily understandable manner. Overall, Gazelle-Multispectral enables affordable, rapid, and accurate NBS for SCD at the POC in low resource settings where the prevalence of SCD is high.Figure 1. Gazelle-Multispectral for screening hemoglobin variants in newborns. (A) The Gazelle-Multispectral perform real time imaging and data analysis tracking the Hb electrophoresis process under both white light illumination (B) and UV light illuminaTable 1. Summary of true positive, true negative, false positive, false negative, sensitivity, and specificity of the clinical testing among 294 subjects conducted at Korle Bu Teaching Hospital, Korle Bu, Ghana. P. THOTA declares a conflict of interest: Other: Employee of Hemex Health