According to a study published in the Journal of Biological Psychiatry November 5, 2015, gene deletions and copies at the 16p11.2 BP4-BP5 locus are “highly associated” with autism spectrum disorder and schizophrenia. The study assessed the effects of “62 deletion carriers, 44 duplication carriers and 71 intrafamilial control subjects.”
Results of the study showed that although IQ was decreased for both deletion carriers and duplication carriers, there was variance in language, verbal memory and inhibition between the two types of carriers. Deletion carriers had “severe impairments of phonology and of inhibition skills beyond what is expected for their IQ level.” However, for those with gene duplication, “verbal memory and phonology” was improved compared to the control subjects.
The study authors note that further research is needed to replicate the findings regarding this gene locus associated with autism and to explain the molecular mechanisms that affect these types of cognition.
Update 2019: The ∼600 kb 16p11.2 BP4-BP5 gene deletion is one of the most common causes of autism. Research studies are being done on people who are deletion carriers to assess full scale intelligence quotient (FSIQ) and verbal IQ as compared to non-carriers.