A spokesperson for the popular YouTube star confirmed his death on Thursday (December 29). The cause of death has not been disclosed. Keenan revealed just a few weeks ago that he would be undergoing open heart surgery on December 15th. While it is unclear why he was undergoing open heart surgery, it could have been related to his Maroteaux-Lamy syndrome. According to Medline Plus, the disease is “a progressive condition that causes many tissues and organs to enlarge, become inflamed or scarred, and eventually waste away (atrophy). Heart disease is a leading cause of death in people with Maroteaux-Lamy syndrome. Keenan became popular online after he began uploading lip sync videos to YouTube in 2010. Since then, he has had some big names appear on his channel, including Justin Bieber, Katy Perry, 50 Cent, and even Jennifer Aniston. Keenan also appeared in Sara Bareilles’ music video for “Uncharted”! During this difficult time, our hearts go out to his family and loved ones.