The truth about complex traits and GWAS

This 2017 Colorado analysis, “No Evidence That Schizophrenia Candidate Genes Are More Associated With Schizophrenia Than Noncandidate Genes,” found: “A recent analysis of 25 historical candidate gene polymorphisms for schizophrenia in the largest genome-wide association study [GWAS] conducted to date suggested that these commonly studied variants were no more associated with the disorder than would be … Continue reading The truth about complex traits and GWAS

Hidden hypotheses of epigenetic studies

This 2018 UK review discussed three pre-existing conditions of epigenetic genome-wide association studies: “Genome-wide technology has facilitated epigenome-wide association studies (EWAS), permitting ‘hypothesis-free’ examinations in relation to adversity and/or mental health problems. Results of EWAS are in fact conditional on several a priori hypotheses: EWAS coverage is sufficient for complex psychiatric problems; Peripheral tissue is … Continue reading Hidden hypotheses of epigenetic studies

Common features of autoimmune diseases

This 2018 French review subject was mechanisms of autoimmunity: “Autoimmune diseases (AIDs) encompass more than 80 distinct chronic disorders characterized by inflammatory reactions that can either be systemic or organ specific. In all cases, the disease development is the consequence of the effects of environmental factors in predisposed individuals. Most of the genes identified by … Continue reading Common features of autoimmune diseases

Resiliency in stress responses

This 2018 US Veterans Administration review subject was resiliency and stress responses: “Neurobiological and behavioral responses to stress are highly variable. Exposure to a similar stressor can lead to heterogeneous outcomes — manifesting psychopathology in one individual, but having minimal effect, or even enhancing resilience, in another. We highlight aspects of stress response modulation related … Continue reading Resiliency in stress responses

A study of gene-environment interactions

This 2018 Hungary/UK study used Bayesian analysis to better understand gene-environment interactions that produce depression: “Most genetic studies do not consider the effect of stressors which may be one reason for the lack of replicable results in candidate gene studies, GWAS [genome-wide association studies] and between human studies and animal models..Animal models of depression usually … Continue reading A study of gene-environment interactions

Epigenetics research and evolution

This 2017 UK essay was a longish review of how epigenetics and other research has informed evolutionary theory: “There are several processes by which directed evolutionary change occurs—targeted mutation, gene transposition, epigenetics, cultural change, niche construction and adaptation. Evolution is an ongoing set of iterative interactions between organisms and the environment..Directionality is introduced by the … Continue reading Epigenetics research and evolution

A review of biological variability

This 2017 UK/Spanish review subject was biological variability: “No two cells in a cellular population are the same, and no two individuals of a multi-cellular species are identical-not even if they share the same genetic makeup like monozygotic twins or cloned animals. Epigenetic and gene expression variability are key contributors to phenotypic differences. There are … Continue reading A review of biological variability

Epigenetic consequences of early-life trauma: What are we waiting for?

This 2015 UK human review discussed: “The progress that has been made by studies that have investigated the relationship between depression, early trauma, the HPA axis and the NR3C1 [glucocorticoid receptor] (GR) gene. Gene linkage studies for depression, as well as for other common complex disorders, have been perceived by some to be of only … Continue reading Epigenetic consequences of early-life trauma: What are we waiting for?

Improved methodology in studying epigenetic DNA methylation

This 2015 New York human study was of: “The two major populations of human prefrontal cortex neurons..the excitatory glutamatergic projection neurons and the inhibitory GABAergic interneurons which constitute about 80% and 20% of all cortical neurons, respectively. Major differences between the neuronal subtypes were revealed in CpG, non-CpG and hydroxymethylation (hCpG). A dramatically greater number … Continue reading Improved methodology in studying epigenetic DNA methylation

A problematic study of DNA methylation in frontal cortex development and schizophrenia

This 2015 Baltimore human study found: “CpGs that differ between schizophrenia patients and controls that were enriched for genes related to development and neurodifferentiation. The schizophrenia-associated CpGs strongly correlate with changes related to the prenatal-postnatal transition and show slight enrichment for GWAS [genome-wide association study] risk loci while not corresponding to CpGs differentiating adolescence from … Continue reading A problematic study of DNA methylation in frontal cortex development and schizophrenia