Rethinking the Genetic Theory of Inheritance: CAMH study reveals that heritability may not be limited to DNA



    TORONTO, Jan. 19 /CNW/ - Scientists at the Centre for Addiction and
Mental Health (CAMH) have detected evidence that DNA may not be the only
carrier of heritable information; a secondary molecular mechanism called
epigenetics may also account for some inherited traits and diseases. These
findings challenge the fundamental principles of genetics and inheritance, and
potentially provide a new insight into the primary causes of human diseases.
    Your mother's eyes, your father's height, your predisposition to disease
- these are traits inherited from your parents. Traditionally, 'heritability'
is estimated by comparing monozygotic (genetically identical) twins to
dizygotic (genetically different) twins. A trait or disease is called
heritable if monozygotic twins are more similar to each other than dizygotic
twins. In molecular terms, heritability has traditionally been attributed to
variations in the DNA sequence.
    CAMH's Dr. Art Petronis, head of the Krembil Family Epigenetics
Laboratory, and his team conducted a comprehensive epigenetic analysis of 100
sets of monozygotic and dizygotic twins in the first study of its kind. Said
Dr. Petronis, "We investigated molecules that attach to DNA and regulate
various gene activities. These DNA modifications are called epigenetic
factors."
    The CAMH study showed that epigenetic factors - acting independently from
DNA - were more similar in monozygotic twins than dizygotic twins. This
finding suggests that there is a secondary molecular mechanism of heredity.
The epigenetic heritability may help explain currently unclear issues in human
disease, such as the presence of a disease in only one monozygotic twin, the
different susceptibility of males (e.g. to autism) and females (e.g. to
lupus), significant fluctuations in the course of a disease (e.g. bipolar
disorder, inflammatory bowel disease, multiple sclerosis), among numerous
others.
    "Traditionally, it has been assumed that only the DNA sequence can
account for the capability of normal traits and diseases to be inherited,"
says Dr. Petronis. "Over the last several decades, there has been an enormous
effort to identify specific DNA sequence changes predisposing people to
psychiatric, neurodegenerative, malignant, metabolic, and autoimmune diseases,
but with only moderate success. Our findings represent a new way to look for
the molecular cause of disease, and eventually may lead to improved
diagnostics and treatment."
    More information on this study is available on the <a href="http://www.nature.com/ng/index.html">Nature Genetics</a>
website. <a href="http://www.camh.net/News_events/Media_centre/video/epigenetics_jan09_launch.html">Visit Rethinking the Genetic Theory of Inheritance for a video of Dr.</a>
<a href="http://www.camh.net/News_events/Media_centre/video/epigenetics_jan09_launch.html">Petronis discussing this groundbreaking discovery</a>.

    The Centre for Addiction and Mental Health (CAMH) is Canada's largest
mental health and addiction teaching hospital, as well as one of the world's
leading research centres in the area of addiction and mental health. CAMH
combines clinical care, research, education, policy development and health
promotion to transform the lives of people affected by mental health and
addiction issues.
    CAMH is fully affiliated with the University of Toronto, and is a Pan
American Health Organization/World Health Organization Collaborating Centre.





For further information:

For further information: To arrange interviews please contact Michael
Torres, Media Relations, CAMH at (416) 595-6015


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