Yes, I read some of their stories online. The cases I read were from people with Asperger Syndrome or High Functioning Autism. Having said that I heard of a recent policy that those with this type of disabilities are honorably excused from serving. Of course, this does not stop them from serving alternative missions or service missions part-time, following the same rules as a regular missionary, wearing a name tag and getting a plaque when they are released honorably.