Genetic Mental Health Disorders

Psychiatric disorders often overlap and can make diagnosis difficult. Depression and anxiety, for
example, can coexist and share symptoms. Schizophrenia and anorexia nervosa manifesting
together is another example. Autism and attention deficit/hyperactivity disorder as well. Why is
that?

Life experiences, environment, and genetics can all influence psychiatric disorders, but much of
it comes down to variations in our genetics. Over the past few years, scientists in the field of
psychiatric genetics have found that there are common genetic threads that may be linking and
causing coexisting psychiatric disorders.

Genes are segments of deoxyribonucleic acid (DNA), the biological blueprint for proteins that
form the building blocks of our cells. Your DNA is passed down from your biological parents and
varies a little from person to person. These variations contribute to differences in appearance,
personality, and health. Certain genes, along with biological and environmental factors, can be
associated with mental disorders, which are health conditions that can affect how you think,
feel, and cope with life.

Common mental disorders like depression and anxiety are likely the result of a combination of
life experiences, environment, and genetic variation. These variations can impact how your
genes are turned “on” and “off” throughout life and play a role in the onset of some diseases.
Most genetic variants don’t directly cause mental disorders. However, in rare cases, some
uncommon gene variants can increase the risk of developing mental disorders. If you or a
relative has one of these rare variants, it’s a good idea to talk to a health care provider about
the risks.

The disorders are grouped into categories, each with a shared genetic architecture, including:

− Disorders with compulsive features such as anorexia nervosa, Tourette’s disorder, and
obsessive-compulsive disorder (OCD).
− Internalizing conditions including depression, anxiety, and post-traumatic stress disorder
(PTSD).
− Substance use disorders.
− Neurodevelopmental conditions, including autism and attention-deficit/hyperactivity
disorder (ADHD).

Some major mental illnesses, such as autism, attention deficit-hyperactivity disorder, bipolar
disorder, major depressive disorder and schizophrenia appear to share some common genetic

risk factors, according to an examination of genetic data from more than 60,000 people
worldwide, according to a study published in The Lancet.

Building off previous groundbreaking research, a new study identifies specific genetic variants
that have significant impacts on brain development and are shared across eight different
psychiatric disorders. Targeting these variants could pave the way for treatments that address
multiple conditions at once.

In 2019, an international team of researchers at the UNC School of Medicine and the Psychiatric
Genomics Consortium conducted genome-wide association studies (GWAS) on eight disorders:
autism spectrum disorder, attention deficit/hyperactivity disorder (ADD), schizophrenia, bipolar
disorder, major depressive disorder, Tourette’s syndrome, obsessive-compulsive disorder
(OCD), and anorexia nervosa, to better understand the shared genetic underpinnings between
psychiatric disorders.

In 2019, researchers at the Psychiatric Genomics Consortium, Harvard University, and the UNC
School of Medicine identified 136 hot spots within the genome that are associated with eight
psychiatric disorders. Among them, 109 hot spots were shared among multiple disorders.
However, it was not clear at the time how genetic variations within these hot spots differed
from those that only have roles in only one disorder.

A new genetic study, led by Hyejung Won, PhD, associate professor in the Department of
Genetics and the UNC Neuroscience Center, and Patrick Sullivan, MD, FRANZCP, the Yeargen
Distinguished Professor of Psychiatry and Genetics, has successfully delineated the functional
consequences of genetic variants into two groups. Their findings, which were published in Cell,
suggest that the discovered variants may be optimal targets for treatment due to their
extended roles in development and sensitivity to change.

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6960.