As a suggestion for biomart, maybe in future versions when making a query it should return a message indicating the genome version that was used. Now that GRCm39 is out and the default I guess many people will run into coordinate incompatibilities as they assume it was still GRCm38. With a little message users will notice the mistake right away. I ran into it myself recently as I missed that 39 is now default. - Alexander Toenges in BioC Slack