2,000 human brains yield clues to how genes raise risk for mental illnesses
Reporter: Irina Robu, PhD
It’s one thing to detect sites in the genome associated with mental disorders; it’s quite another to discover the biological mechanisms by which these changes in DNA work in the human brain to boost risk. In their first concerted effort to tackle the problem, 15 collaborating research teams of the National Institutes of Health-funded PsychENCODE Consortium evaluated data of 2000 human brains which might yield clues to how genes raise risk for mental illnesses.
Applying newly uncovered secrets of the brain’s molecular architecture, they established an artificial intelligence model that is six times better than preceding ones at predicting risk for mental disorders. They also identified several hundred previously unknown risk genes for mental illnesses and linked many known risk variants to specific genes. In the brain tissue and single cells, the researchers identified patterns of gene expression, marks in gene regulation as well as genetic variants that can be linked to mental illnesses.
Dr. Nenad Sestan of Yale University explained that “ the consortium’s integrative genomic analyses elucidate the mechanisms by which cellular diversity and patterns of gene expression change throughout development and reveal how neuropsychiatric risk genes are concentrated into distinct co-expression modules and cell types”. The implicated variants are typically small-effect genetic variations that fall within regions of the genome that don’t code for proteins, but instead are thought to regulate gene expression and other aspects of gene function.
In addition to the 2000 postmortem human brains, researchers examined brain tissue from prenatal development as well as people with schizophrenia, bipolar disorder, and typical development compared findings with parallel data from non-human primates. Their findings indicate that gene variants linked to mental illnesses exert more effects when they jointly form “modules”, communicating genes with related functions and at specific developmental time points that seem to coincide with the course of illness. Variability in risk gene expression and cell types increases during formative stages in early prenatal development and again during the teen years. However, in postmortem brains of people with a mental illness, thousands of RNAs were found to have anomalies.
According to NIMH, Geetha Senthil the multi-omic data resource caused by the PsychENCODE collaboration will pave a path for building molecular models of disease and developmental processes and may offer a platform for target identification for pharmaceutical research.
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