Is there a molecular basis to intelligence?
As a Drosophila biologist, I will attempt to address the above question by giving an examples from the Drosophila field. When this paper (http://www.ncbi.nlm.nih.gov/pubmed/7720066) in Cell came out, it sent shockwaves around the world since it showed a molecular mechanism by which production of cAMP and activation PKA, effects CREB transcriptional activation and in turn formation of the long-term memory (LTM) in flies. Some of these CREB over expressing flies could learn a task after simply one try whereas wild-types had to do it several times! This work was later followed by mouse studies (http://www.pnas.org/content/100/18/10518.full.pdf) and comparisons to RTS patients were made. At that time there were discussions of CREB being responsible for intelligence however now there is nice nature review/meta-analysis paper (http://www.nature.com/srep/2014/140225/srep04176/pdf/srep04176.pdf), which says there are no evidence connecting CREB and IQ. This paper performs a literature based investigation and identifies several candidates that are testable and can act as biomarkers for intelligence related therapeutic approach to mental retardation. According to their screen dopamine and norepinephrine pathways seems to be important in IQ-related biological processes.

Hope this helps!