Christina Applegate, Selma Blair, Jamie-Lynn Sigler, Jack Osbourne and many other celebrities have opened up about dealing with multiple sclerosis, an autoimmune disease. Applegate revealed in August 2021 that she was diagnosed with the condition. "Hi friends. A few months ago, I was diagnosed with MS," the Married ... With Children alum wrote via X at the time. "It's been a strange journey. But I have been so supported by people that I know who also have this condition. It's been a tough road. But as we all know, the road keeps going. Unless some a**hole blocks it.