Eric Dane opened up about his recent ALS diagnosis on "Good Morning America," telling Diane Sawyer that he now only has "one functioning arm."

Actor Eric Dane is opening up about living with ALS. In his first television interview since revealing he has amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s Disease, Dane, 52, recalled the symptoms that led to discovering his diagnosis about a year and a half ago.

Eric Dane, an actor best known for playing Dr. Mark Sloan, aka "McSteamy," on "Grey's Anatomy," discussed his health challenges after being diagnosed with ALS.