Ask HN: Are user names personal information?

Setting facebook's real name policy aside, is there case law in which user names are defined as personal information. As an example, consider the following. Reddit has a policy in which users should not post personal information, especially about other users. A gaming subreddit deletes links to videos/screen-shots that contain gamer tags claiming gamer tags are personal information. Clearly this is policy rather than law, but often law influences policy. Is it reasonable to consider user names to be personal information?