In this photo taken April 6, 2011, Keenan Cahill, 16, poses outside his home in Elmhurst, Ill., with his mother Erin O'Brien-Cahill, and sister Katherine. Cahill has a rare genetic disorder called ... more 
In this photo taken April 6, 2011, Keenan Cahill, 16, poses outside his home in Elmhurst, Ill., with his mother Erin O'Brien-Cahill, and sister Katherine. Cahill has a rare genetic disorder called Maroteaux-Lamy Syndrome, also known as MPS, type 6. Diagnosed at age 2, he has had multiple surgeries because of the illness and has only grown to the height of 4-foot-1. Cahill has become a YouTube sensation in the past three years after posting videos of himself lip-syncing to popular songs. Now celebrities come to him to help them promote their songs and products that they endorse. less 
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Associated Press | Photo By M. Spencer Green
Mon, Apr 18, 2011 3:21 AM EDT