Autism is typically thought of as a neurodevelopmental disorder. It is assumed that something goes wrong early in a child's development and that the brain doesn't develop properly and that the result is permanent.
But what if that wasn't the case?
According to some recent research, the symptoms of Rett Syndrome (a form of autism) might caused by the continuing lack of the protein MeCP2 rather than problems with growth and development of the brain caused by the lack of MeCP2. If that seems like splitting hairs, it really isn't. That simple distinction means that Rett's might not be a neurodevelopmental disorder after all.
More logical and more probable:
What if Rett's isn't a form of autism at all but just something that looks like it?
Strange people, they accept something as a fact and then when that thing doesn't conform to the majority of Autism cases one assumes that therefore that autism is more like the thing instead of reaching the obvious conclusion the the thing was wrongly classed.
Never ceases to amaze me.