What Is the Meaning of Epigenetics?
Researchers in epigenetics, a sub-field of genetics, study heritable changes in gene function occurring without changing the DNA sequence. Choices made by animals and/or humans in areas such as diet and activity levels cause chemical reactions that affect epigenetic markers that turn on or off one or more genes in the genome.
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Personal Choices
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Another epigenetic discovery is that personal choices made by expectant mothers can affect fetal development, as well as the adult health of a child, according to the results of a 1986 study published in the journal "Lancet." Further research by Dr. Lars Olov Bygren has shown that events occurring before conception, including events in a parent's childhood, can affect epigenetic markers that can translate to changes in the parent's genes that pass along to the offspring.
Nature and Nurture
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The field of epigenetics has shown that rather than a case of nature vs. nurture, an organism's development is based on both nature and nurture. Although DNA decides certain traits such as eye color, permanently, environment shapes other traits such as how calm or anxious you are in stressful situations. A 2004 McGill University study published in "Nat. Neuroscience" reported that maternal nurturing behavior can affect the epigenotype. In the McGill study, mother rats who often licked their pups during the first week of life raised calm pups; the mother rats who licked less often or not at all raised anxious pups. As adults, the female pups copied their mother's behavior as a mother due to their epigenetic programming.
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Inherited Epigenome
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Until recently, geneticists believed each organism began life with an epigenetic blank slate, but according to the University of Utah, some epigenetic tags--about 1 percent in mammals--pass from generation to generation via epigenetic inheritance, also referred to as imprinting. A parent's experiences can pass down to offspring, bypassing the egg and/or sperm and therefore, avoiding the epigenetic purging occurring in early fetal development.
Changing Genetic Traits
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Although parental environmental factors can influence an offspring's gene expression, some expressions can be altered or reversed in the womb. For instance, expectant mothers who take methyl-donating substances such as vitamin B12, folic acid, choline, betaine or genistein can counteract reductions in DNA methylation caused by high exposure to BPA, a substance present in common plastics. Other epigenetic changes can occur after birth. In the McGill study, scientists reversed the epigenetic programming of second generation mother rats in adulthood using histone deacetylase (HDAC) inhibitor treatments or methionine supplementation.
Medical Implications
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Doctors use epigenetic therapies to treat some cancers by inhibiting the DNA methyltransferases. Another epigenetic therapy applied to neurological disorders, such as bipolar disorder, can boost the effectiveness of anti-psychotic drugs using the histone deaceitylase (HDAC) inhibitor, valproic acid. HIV and AIDS researchers know that some people have a natural immunity to the disease and are working to identify the genetic markers for resistance. Once identified, scientists will look at potential epigenetic therapies.
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