Analytical Validation of an ELISA assay for Maternal Autoantibody Related Autism

BackgroundThe influence of genetic and environmental factors, especially during early development, is critical in the pathogenesis of autism. Maternal autoantibodies that recognize specific fetal brain proteins can be strong predictors of autism risk. These antibodies cross the placenta and bind to their target antigens, which play critical roles in neurodevelopment, thereby increasing autism risk. This etiologically defined subtype is now referred to as Maternal Autoantibody-Related Autism (MARA). The newly developed MAR-AutismTM test is an indirect multi-ELISA assay designed to detect specific combinations of these maternal antibodies, which strongly predicts increased autism risk. ObjectiveTranslation of the indirect ELISA assays for the eight relevant antibodies (LDH-A, LDH-B, GDA, STIP1, CRMP1, CRMP2, NSE and YBOX) from an academic laboratory to a clinical development laboratory for optimization and determination of the analytical performance of the individual antibody assays. MethodsFeasibility assays were transferred from the academic laboratory and their performance confirmed prior to optimization of all steps from target protein production to preliminary threshold determination. Validation to rigorous standards was conducted. The ELISAs are qualitative assays using an internal continuous response and a cutoff to define positivity and negativity for each analyte. Analytical performance metrics of linearity, sensitivity, specificity, precision, and stability were determined by standard testing methodologies. ResultsThe optimized ELISAs all performed at acceptable standards for analytical performance. All of the assays except one were demonstrated to be linear upon dilution with buffer and with non-reactive plasma, however, recovery was overestimated with buffer diluent. The precision profile results demonstrated that the Lower Limit of Quantification (LOQ) was greater than the Limit of Detection (LOD) and below the preliminary thresholds determined from a general population cohort distribution. Precision studies showed coefficients of variation less than 15% with two minor exceptions. Common interfering substances, apart from whole human IgG, did not affect assay performance. The microtiter assay plates were stable for at least 6 months without significant drift. ConclusionOverall, the individual antibody assays demonstrated high sensitivity, specificity, and robustness sufficient to enable extension to clinical validation. These assays enable evaluation of specific antibody combinations that were previously reported to strongly and specifically correlate with autism risk, particularly in settings of suspected diagnosis or in families with an older sibling with a confirmed autism diagnosis.