Imaging genetics refers to the use of anatomical or physiological imaging technologies as

phenotypic In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...

assays An assay is an investigative (analytic) procedure in laboratory medicine, mining, pharmacology, environmental biology and molecular biology for qualitatively assessing or quantitatively measuring the presence, amount, or functional activity of a ...

to evaluate genetic variation. Scientists that first used the term imaging genetics were interested in how genes influence psychopathology and used

functional neuroimaging Functional neuroimaging is the use of neuroimaging technology to measure an aspect of brain function, often with a view to understanding the relationship between activity in certain brain areas and specific mental functions. It is primarily used a ...

to investigate genes that are expressed in the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

(neuroimaging genetics). Imaging genetics uses research approaches in which genetic information and

fMRI Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area ...

data in the same subjects are combined to define neuro-mechanisms linked to genetic variation. With the images and genetic information, it can be determined how individual differences in single nucleotide polymorphisms, or SNPs, lead to differences in brain wiring structure, and intellectual function. Imaging genetics allows the direct observation of the link between genes and brain activity in which the overall idea is that common variants in SNPs lead to common diseases. A neuroimaging

phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological pr ...

is attractive because it is closer to the biology of genetic function than illnesses or cognitive phenotypes.

Alzheimer's disease

By combining the outputs of the polygenic and neuro-imaging within a linear model, it has been shown that genetic information provides additive value in the task of predicting Alzheimer's disease (AD). AD traditionally has been considered a disease marked by neuronal cell loss and widespread gray matter atrophy and the apolipoprotein E allele (

APOE4 Apolipoprotein E (APOE) is a protein involved in the metabolism of fats in the body of mammals. A subtype is implicated in Alzheimer's disease and cardiovascular disease. APOE belongs to a family of fat-binding proteins called apolipoproteins. ...

) is a widely confirmed genetic risk factor for late-onset AD. Another gene risk variant is associated with Alzheimer's, which is known as the CLU gene risk variant. The CLU gene risk variant showed a distinct profile of lower white matter integrity that may increase vulnerability to developing AD later in life. Each CLU-C allele was associated with lower FA in frontal, temporal, parietal, occipital, and subcortical white matter. Brain regions with lower FA included corticocortical pathways previously demonstrated to have lower FA in AD patients and APOE4 carriers. CLU-C related variability found here might create a local vulnerability important for disease onset. These effects are remarkable as they already exist early in life and are associated with a risk gene that is very prevalent (~36% of Caucasians carry two copies of the risk conferring genetic variant CLU-C.) Quantitative mapping of structural brain differences in those at genetic risk of AD is crucial for evaluating treatment and prevention strategies. If the risk for AD is identified, appropriate changes in lifestyle may limit the apprehension of AD; exercise and body mass index-have an effect on brain structure and the level of brain atrophy

Biomarkers and Alzheimer's spectrum

If suitable biomarkers are found and applied in clinical use, we will be able to give the diagnosis of the AD spectrum at an even earlier stage. In the proposal, the AD spectrum is divided into the three stages (i) the preclinical stage; (ii) mild cognitive impairment; and (iii) clinical AD. In the preclinical stage, only changes in a specific biomarker are observed with neither cognitive impairment nor clinical signs of AD. The mild cognitive impairment stage may include those showing biomarker changes as well as mild cognitive decline but no clinical signs and symptoms of AD. AD is diagnosed in patients with biomarker changes and clinical signs and symptoms of AD. This concept will promote understanding of the continuous transition from preclinical stage to AD via mild cognitive impairment, in which biomarkers can be utilized to discriminate and clearly define each stage of the AD spectrum. The new criteria will promote earlier detection of the subjects who will develop AD in later life, and also to initiate intervention aiming for the prevention of AD.

Future

Imaging genetics must develop methods that will allow relating the effects of a large number of genetic variants on equally multi-dimensional neuroimaging phenotypes. Additionally, the field of imaging epigenetics is emerging with particular relevance, for example, to the understanding of intergenerational transmission of trauma-related psychopathology and related disturbances of maternal care.

Problems

Medication, hospitalization history, or associated behaviors ranging such as smoking can affect imaging.

Notes

External links

International Imaging Genetics Conference website
{{Psychiatry Genetics Neuroscience