Christina Applegate Says She Was Misdiagnosed With MS

For the last five years, Christina Applegate believed she had multiple sclerosis but now she says her doctor told her that she was misdiagnosed.

The actor, who has been an outspoken advocate for MS research, said the news was "unnerving" and "confusing." NBC’s Emilie Ikeda reports and Dr.

Natalie Azar joins TODAY to discuss what causes a misdiagnosis and how common it is.