(WGN) – Popular YouTube personality Keenan Cahill passed away Thursday at the age of 27, according to a spokesperson for the family.

Cahill had Maroteaux–Lamy syndrome and had posted on social media that he was having open heart surgery on December 15. Maroteaux-Lamy syndrome is a progressive condition that causes many tissues and organs to enlarge, become inflamed or scarred, and eventually waste away (atrophy), according to MedlinePlus. Patients with the syndrome can also have cardiac problems that typically include heart valve abnormalities.

Cahill became one of the first internet sensations when he started uploading lip-synched videos to YouTube in 2010. His clips grabbed the attention of celebrities including Jimmy Kimmel and Katy Perry.

Perry, Jennifer Aniston, 50 Cent, Justin Bieber, and other famous fans later appeared on his YouTube channel. Cahill himself also appeared in Sara Bareilles’ music video for “Uncharted” alongside Adam Levine, Pharrell Williams, and Josh Groban, among others.

Cahill’s YouTube videos had amassed over 500 million views. He released his own original music through his channel, as well.