By default, the forum does not send notification messages about new comments or discussions. If you want to turn on notifications or customize the type of notifications you want to receive (email, popup message etc), you need to do the following:
Go to your profile page by clicking on your username in the white box at the top left corner, underneath the blue path box;
Click on the button with a silhouette of a person at the top right corner and select "Edit Profile" in the drop-down menu;
In the menu on the left, click on "Notification Preferences";
Select the categories that you want to follow and the type of notification you want to receive; For example, to specifically get new GATK announcements, scroll down to "Category Notifications" and tick off the "Announcements" category for email notification for discussions (and comments if you really want to know everything).