The LaTeX Community

I'm using the acronym package for my dissertation and I'm fairly happy with it, except for one thing - you can't seem to switch between capital and lowercase letters. The acronym section in the front matter is written in capital letters, to show where an abbreviation comes from (Example: MMORPG - Massively Multiplayer Online Role Playing Game). But sometimes I'd like to write the acronym in lowercase letters, for instance, when it is used in the middle of a sentence (Example: Games such as massively multiplayer online role playing games...).

Does anyone know how to archive this effect? I tried the \lowercase command (Example: \lowercase{\acl{mmo}}, but it doesn't have any effect. Any help and suggestions are greatly appreciated.