Abstract
Purpose: :
Genome-wide association studies (GWAS) use high-throughput genotyping technologies to search for associations between phenotypic traits and single nucleotide polymorphism (SNP) markers distributed throughout the genome. In the past five years, the GWAS approach has been applied to visual pathologies, such as age-related macular degeneration, corneal dystrophy, and high myopia. GWA studies of psychiatric disorders — including disorders associated with visual abnormalities, such as schizophrenia, dyslexia and childhood autism — have also become common. However, no GWA study to date has investigated the genetic basis of normal variation in visual perception.
Methods: :
In the PERGENIC project, 1060 participants completed a 2.5-hour psychophysical battery that included a range of visual, auditory and psychomotor tasks. Each participant gave a saliva sample, from which DNA was extracted. DNA was then processed on a high-density genotyping assay. Following stringent quality control, our final genetic data set comprised 642 758 SNP markers for 988 individuals. Here, we describe the resulting GWA analyses for two psychophysical measures of visual temporal processing: contrast thresholds for detection of "frequency-doubled" (high temporal frequency, low spatial frequency) luminance gratings; and coherence thresholds for discrimination of motion direction in dynamic random-dot arrays.
Results: :
Across the two measures, we found significant associations (p < 5 x 10–7) for three SNPs, and suggestive associations (p < 10–5) for a further 16 SNPs. We identified 12 independent association signals, six for "frequency-doubled" gratings and six for coherent motion. The associated regions include both genes and non-coding regulatory elements — some with a known role in the visual system, others not previously implicated in visual function. Gene ontology analysis also revealed several functional categories of gene that are over-represented in our set of associations.
Conclusions: :
Our results offer insight into the genetic basis of individual differences in visual temporal processing, and illustrate the considerable potential of GWA studies to advance the understanding of visual perception and its development.
Keywords: temporal vision • motion-2D • genetics