Ms. Bernhardt was born with several broken bones and a collapsed lung, the result of a rare genetic bone disease called osteogenesis imperfecta, also known as brittle bone disease, which left her in a wheelchair for much of her life. Norman Lear, the prolific television producer behind hits such as “All in the Family,” cast Ms. Bernhardt to be a friend of Arnold Jackson, the young star of the show portrayed by Gary Coleman.