HGG Community Forums

There is a helpful explanation about KP and DP (with pictures) over here (you'll need to scroll up to the beginning tho!): http://www.huntandjump.com/forum/discussion/comment/6098#Comment_6098

In short KP stands for KIT promotor, which means that when a horse has two KIT genes (for example sabino tobiano, or homozygous sabino) and is homozygous KP the horse will get random white patches/clouds over its body.

DP stands for Dense Pheomelanin. It only affects red based (ee) horses. It can turn them into liver chestnuts, or when homozygous and with a double dose of ssty even in dark black chestnuts! But without any ssty you still see a difference in coat color compared to chestnuts/palomino's without DP! If you click the above link you'll find some pictures explaining them.

But really the above links says it all :p

If you want to know more about DP; here is the official announcement: http://www.huntandjump.com/forum/discussion/2494/new-gene-added-to-the-game-plus-updates-to-flaxen-silver-and-cream-horse-manes-and-tails-#Item_25