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Nearly a quarter million deaths occur each year in low- and middle-income countries (LMICs) due to inadequate newborn screening for the inherited hemoglobinopathy, sickle cell disease (SCD). Most of these deaths would be prevented with early diagnosis and initiation of appropriate SCD medical care, including antibiotic prophylaxis for the increased risk of severe bacterial infections in SCD, and early recognition and treatment of life-threatening SCD complications such as splenic sequestration and acute chest syndrome. As the healthcare infrastructure in LMICs cannot support laboratory-based newborn screening, a cost-effective point-of-care (POC) SCD diagnostic would be transformative for improving SCD morbidity and mortality. Although some POC SCD tests exist, these utilize proprietary antibodies to detect mutant sickle hemoglobin, and are priced in a manner that prevents utilization in the economically-challenged areas where SCD disease burden is highest. An alternative to antibody-based detection of sickle hemoglobin is detection of the specific beta globin gene mutation in SCD. Cas13 enzymes can rapidly detect single point mutations in RNA and can be produced in bacteria at low-cost. The abundant beta globin messenger RNA (mRNA) in circulating erythrocytes and reticulocytes can potentially provide mutant RNA for Cas13-based detection in SCD patients. Our preliminary work demonstrates that Cas13 detection of beta globin mRNA can be achieved with purified RNA from submicroliter volumes of human blood. Here we propose to develop a POC workflow for Cas13-based detection of SCD-mutant beta globin mRNA from human blood that is deployable in LMICs. We will develop methods for biochemically treating microliter or submicroliter volumes of human blood to release mRNA from erythrocytes and reticulocytes into solution, and do so in a fashion where the solution supports Cas13 enzymatic detection. We will then generate cost-effective reporters of Cas13 detection activity that can be visualized in a lateral flow assay (LFA) and will validate our SCD diagnostic platform using SCD and healthy control blood. Upon successfully developing a field-deployable LFA platform for SCD diagnosis, our technology will potentially help prevent the deaths of up to 250,000 children with SCD per year and provide a major step towards achieving global health equity in SCD.
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