The CORD7 Mutation Found in Humans Increases Verbal IQ and Working Memory
Intelligence in its rawest form is not equally distributed among the human population. While many can critically think and problem solve, others lack these skillsets. However, what is known is that just like height, eye color, and the shape of our nose, these phenotypic attributes all stem from our DNA and are no different from human intelligence. Like savants who have photographic memories or can play the piano with surgical precision without having any prior training and only hearing the song once, this ability is due to the way the synapses of their brains are wired; however, many savants are often afflicted with other neurological and developmental issues.
Interestingly, in November 2018, China was the first to report the successful gene editing of twin babies. They used CRISPR to delete the CCR5 in hopes of making the babies immune to HIV. In mice, this gene deletion has been shown to make them more intelligent, and in humans, it improves brain recovery after stroke and enhances their ability to form memories. While it will be at least a decade before any results of this experiment are revealed, this further solidifies the role of our genetics when it comes to how intelligent a person is.
Recently, scientists at the University of Leipzig have uncovered a mutation that damages a synaptic protein. However, this mutation provides a gain of function in the affected people, giving them above-average intelligence. Unfortunately, this mutation causes blindness in the individuals who are affected. Furthermore, it is extremely rare for a mutation to lead to biological improvement within the organism. Many mutations usually lead to loss of function resulting in death.
The CORD7 (cone-rod dystrophy 7) mutation found in humans increases verbal IQ and working memory. This particular autosomal dominant syndrome is driven by a single amino acid exchange located in the C2A domain of RIMS1/RIM1 (Rab3-interacting molecule 1). RIM is responsible for fast, Ca2+-triggered neurotransmitter release and is vital in the presynaptic active zones. To prove this theory, the scientist at Leipzig University, in collaboration with Oxford, used the homologous C2A domain of a Drosophila melanogaster disease model to elucidate the effects of the CORD7 mutation on RIM functionality and synaptic vesicle release.
Using CRISPR/Cas9 to genetically engineer the Drosophila as well as electrophysiological characterization via two-electrode voltage clamps and focal recordings, they found that synaptic vesicle release was more efficient, and the pool of readily available synaptic vesicles had increased. They also observed an increase in presynaptic active zones. These results suggest that physiological changes seen within the animal model may show a similar pathophysiological phenotype in patients affected by this unique mutation, leading to enhanced synaptic vesicle transmission and increased cognitive abilities.