May have an insult from significant illness or clinical events that could have caused this in autism
and in Chiari there can be Pukinje cell loss a Damaged Cerebellum.
The removed tissue could clearly be classified as abnormal.
PCL is found in a number of degenerative brain disorders and when brain tissue is deprived of oxygen.
Interesting.

http://www.conquerchiari.org/subs%20only/Volume%205/Issue%205(1)/Histological%20Tonsils%205(1).asp

Effects of Mercury Purkinje cells.
Degeneration.

Mercury & Purkinje cells.

http://www.springerlink.com/content/p21m39c5nm1epd8n/

irregularity of the Purkinje cell layer in the cerebellum.

http://www.rogerknapp.com/medical/mercury.htm

a generalized cerebellar atrophy is seen with Purkinje cell loss.
Purkinje cells are vulnerable to mercury.
http://www.generationrescue.org/pdf/encephalopathies.pdf

In severe mercury poisoning head size tends to be small and microcephaly.

http://pediatrics.aappublications.org/cgi/content/full/111/3/674

Chiari
Pedigree Dogs Exposed
The links with Vaccine reactions can not be ignored.
It Is a Small Dog Disease many breeds.
Heart trouble.

http://www.cavalierhealth.co.uk/jeffels.htm

skull bones which were still forming at the time of vaccination including the occipital bone which is known to be underdeveloped ....
may have been subject to shock at this sensitive time of vaccination which may have in some way damaged the proper growth of the occipital bone.
damage in their brain as the result of being exposed to mercury in mice research.

http://www.cavaliers.co.uk/articles/SM%20bet%20hargreaves.htm

The Pukinje cells Autism Pukinje Cells Chiari, mercury??
Could it possibly be? brain degeneration disorders.
Damaged bone growth? Is there a link here...
It sure looks like it.

Now POTS going with all these conditions plus Chiari and what about Autistic children?

http://www.dinet.org/what_causes_pots.htm

And what do they have in common effects of Mercury Purkinje cells degeneration?
And have those with Chiari been tested for viruses like maybe XMRV?

http://www.ageofautism.com/2011/10/xmrv-retrovirus-can-infect-brain-cells.html

Study Finds XMRV Retrovirus Can Infect Brain Cells