I haven't looked at your Tuniq cases, but the layout of the V series is just called Inverted ATX, like WoodButcher said.
BTX has a different motherboard layout/size/mounting holes, so don't get it mixed up with a regular ATX mobo flipped turned upside down [and I'd like to take a minute just sit right there, I'll tell you how I became the prince of a town called Bel-Air...]