Next, the extracted and validated substitutions were compared to the originally annotated ChEMBL variants for all assay-target pairs (Figure , step 3, Supplementary Figure ). This step, which we refer to as the annotation feedback loop, was included for three reasons, namely 1) to pinpoint highlights and pitfalls, 2) suggest improvements to the ChEMBL variant annotation pipeline, and 3) to include additional ChEMBL variants and collect the most complete dataset with variant annotated data in the scope of this project. Additionally, it served as a reminder of the non-triviality of the variant annotation process. Given its complexity, the feedback loop is now under review and remains subject to revision. The updated results will be incorporated in a revised version, therefore it is advisable to approach the following preliminary results with caution. Out of the 8,455 assay-target pairs with extracted substitutions, 7,622 (90%) had an identical annotation in ChEMBL. The remaining 833 were missing in ChEMBL, either completely (651) or because they had been flagged as "Undefined mutation" (182). Mismatching variants were further classified to determine their suitability for the VEBD (Supplementary Table , Supplementary Figure ). Assays assessing more than one target were rejected for this analysis, as well as assays testing targets with variation corresponding to alterations or genotypes with ambiguous definitions. If a multiple substituted protein was only partially validated; the annotations were rejected. If a validated amino acid substitution was combined with an insertion/deletion/truncation then the substitution was included for this analysis. Finally, non-substitution patterns that had been incorrectly validated against the WT sequence were identified as potential novel exceptions for improving the pipeline. Subsequently, these 833 entries were manually classified into 648 true positives that represent potential novel annotations missed by ChEMBL, and 185 false positives that arise from substitution extraction errors and will be used to refine the current pipeline. The true positive group was included in the final VEBD. Of note, among these were assay-target pairs with either completely novel extracted substitutions or rescues from previously undefined variants that were not fully annotated but were deemed inside the scope of this project. For example, we deemed as within scope, variants with co-occurring amino acid substitutions and deletions/duplications, flagged by ChEMBL as undefined variants and "rescued" for this project.