Limited availability of live CBA for MOG-IgG testing and its consequences for the diagnosis and treatment of MOGAD in Latin American countries.

In recent years, increasing evidence has highlighted live-cell-based assay (live CBA) as the best available tool for screening for Myelin oligodendrocyte glycoprotein (MOG) autoantibodies (MOG-IgG) during MOG antibody-associated disease (MOGAD). However, in resource-limited settings in Latin America (LATAM), where even commercial kits (fixed CBA) can be scarce, accessing local live CBA is challenging due to its higher costs and technical complexity. In this narrative review, we identified 24 published studies that provide evidence of CBA locally used in LATAM countries. We identified only 4 studies (16.7 %) that used "live CBA" as the exclusive MOG-IgG testing method. Another 7 studies (29.2 %) reported using live CBA in combination with commercial tests ("live CBA and fixed CBA") to detect MOG-IgG. Brazil is the only country that has participated in all published studies using live CBA, either exclusively or alongside a commercial fixed assay. Argentina had the second largest participation in studies combining both methods (n = 4, 16.7 %), followed by Chile (n = 2, 8.3 %), Mexico (n = 2, 8.3 %), Ecuador (n = 2, 8.3 %), Colombia (n = 2, 8.3 %), Venezuela (n = 1, 4.1 %) and Peru (n = 1, 4.1 %), respectively. Our literature review suggests that live CBA availability is 16.7 % when considered as a single testing method, or up to 45.9 % when used to varying degrees in conjunction with fixed CBA. Importantly, more than half of the studies we analyzed (n = 13, 54.1 %) relied solely on commercial fixed assays ("fixed CBA" and "CBA") for MOG-IgG screening. Based on our findings, we critically discuss the pressing need for live CBA dissemination across LATAM countries. This initiative will lead to more accurate epidemiological data, enable faster diagnosis, and improve access to highly effective therapies for MOGAD patients living in this part of the world.