Authorities in Butler County are searching for a 23-year-old man with mental retardation who went missing from his home this morning.

Mark Richard Ryan, of Summit, was last seen in his home on Kaiser Road at 5:30 a.m. He is 5-foot-3, 176 pounds, and is white with brown eyes and brown hair. Police say he has a medium build and is unshaven. Mr. Ryan was last known to be wearing a black No. 7 Ben Roethlisberger Steelers T-shirt, blue jeans and brown sandals.

Police say Mr. Ryan has been diagnosed with moderate mental retardation, autism and exotropia -- meaning one or both eyes turn outward. Mr. Ryan also walks with a severe limp due to muscular tissue distortion in his feet. Police say Mr. Ryan has "limited communication skills and is considered a danger to himself outside of immediate care due to his intellectual disabilities."

A man matching Mr. Ryan's description was seen about 6:55 a.m. on Schuler Road in Clearfield and at 8:30 a.m. near Herman and Osche roads, at the border of Summit and Clearfield.

Anyone with information is asked to call the state police Butler barracks at 724-284-8100 or call 911.