[neverdem]

I should have checked Nature News' links first. They're all lame. Sorry about that. Deletions and duplications of genes are examples of copy-number variation (CNV). It's not simple Mendelian genetics anymore. Here you go.

Rare De Novo and Transmitted Copy-Number Variation in Autistic Spectrum Disorders

Multiple Recurrent De Novo CNVs, Including Duplications of the 7q11.23 Williams Syndrome Region, Are Strongly Associated with Autism

Rare De Novo Variants Associated with Autism Implicate a Large Functional Network of Genes Involved in Formation and Function of Synapses

Solving the Autism Puzzle a Few Pieces at a Time

[Rockingham]

Even worse, methylation often controls which genes are expressed or suppressed, and there is evidence that genes and methylation can vary even within an organ. This seems to be especially true in the brain.