Imaging genetics is an integrated research method that uses neuroimaging and
genetics to assess the impact of genetic variation on brain function and structure. Imaging
genetics is both a tool for the discovery of risk genes for psychiatric disorders and a strategy
for characterizing the neural systems affected by risk gene variants to elucidate quantitative
and mechanistic aspects of brain function implicated in psychiatric disease. Early studies of
imaging genetics included association analyses between brain morphology and single
nucleotide polymorphisms whose function is well known, such as catechol-Omethyltransferase
(COMT) and brain-derived neurotrophic factor (BDNF). GWAS of
psychiatric disorders have identified genes with unknown functions, such as ZNF804A, and
imaging genetics has been used to investigate clues of the biological function of these genes.
The difficulty in replicating the findings of studies with small sample sizes has motivated the creation of largescale
collaborative consortiums, such as ENIGMA, CHARGE and IMAGEN, to collect thousands of images. In
a genome-wide association study, the ENIGMA consortium successfully identified common variants in the
genome associated with hippocampal volume at 12q24, and the CHARGE consortium replicated this finding.
The new era of imaging genetics has just begun, and the next challenge we face is the discovery of small
effect size signals from large data sets obtained from genetics and neuroimaging. New methods and
technologies for data reduction with appropriate statistical thresholds, such as polygenic analysis and parallel
independent component analysis (ICA), are warranted. Future advances in imaging genetics will aid in the
discovery of genes and provide mechanistic insight into psychiatric disorders.
Keywords: Bipolar disorder, genome-wide association study, gene, imaging genetics, intermediate phenotype,
neuroimaging, schizophrenia, structural MRI.
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