>>23
Autism is caused by a smaller subset of genes than those that define race, species, and genus.
Autism is more prevalent in Western Europeans, who are derived from Haplogroup CT and Homo Neanderthal hybridization.
Recently (as in, just last week), certain genes involved with brain volume and autism were discovered.
http://www.ncbi.nlm.nih.gov/pubmed/22729224
http://www.medicalnewstoday.com/articles/247396.php
This ties in with last year's discovery of another gene also responsible for cranial volume, intelligence, and certain brain disorders.
Larger cranial volume is directly tied with increased intelligence, and intelligence is mostly heritable. We are not all equal.
http://www.nature.com/mp/journal/v16/n10/full/mp201185a.html
http://www.nature.com/ng/journal/vaop/ncurrent/full/ng.2250.html
http://www.nature.com/ng/journal/vaop/ncurrent/full/ng.2237.html
http://www.sciencemag.org/content/309/5741/1717.abstract
http://newsroom.ucla.edu/portal/ucla/international-team-uncovers-new-231989.aspx
https://gene.sfari.org/GeneDetail/CNTNAP2#HG
Of interest is the CNTNAP2 genes.
Here we can see that the rs10784502 (T allele) variant of the CNTNAP2 gene associated with increased cranial volume has a greater frequency in East-Asian and Indo-European populations, and less in most African populations:
http://www.ncbi.nlm.nih.gov/SNP/snp_ref.cgi?rs=rs10784502
So increased levels of intelligence within a given race also come with the cost of increased frequency of autism.