Dane -- who shot to fame amid six seasons on the hit ABC drama "Grey's Anatomy," where he played Dr. Mark Sloan, affectionately known as "McSteamy" -- said his symptoms began over one year ago, when he began to experience weakness in his right hand.

Eric Dane is not backing down from his fight against ALS. The 52-year-old sat down with ABC News' Diane Sawyer in an interview for Good Morning America, where he revealed his first symptoms of the debilitating disease and how he plans to slow the effects.