Genetic diagnostic laboratories classify DNA sequence variants based on available evidence, following guidelines for variant interpretation. Despite guidelines, laboratories may differ in how they classify the same variant, for example because of differences in how they apply the interpretation criteria. The Canadian Open Genetics Repository (COGR) is an online collaborative effort for data sharing and variant interpretation. Through COGR, laboratories shared variants to identify discordant variant interpretations. Laboratories reassessed their discordant variants to determine whether they could be reclassified. From baseline (before data sharing) to after data sharing and reassessment, concordance in variant classifications improved. This study highlights the importance of data sharing and periodic reassessment to improve concordance in variant interpretations across laboratories. Quality assurance programs such as COGR provide a standardized mechanism for laboratories to identify discordant variant interpretations, and are important as genetic testing is implemented more widely in clinical care. (By Chloe Mighton, MSc, https://jmg.bmj.com/content/early/2021/04/19/jmedgenet-2021-107738 )