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Hello, my name is Marisa Bartolomei.
I'm a professor at the University of Pennsylvania School of Medicine,
in Philadelphia, Pennsylvania in the United States.
This lecture covers the topics of Epigenetics and Inheritance.
First, we will describe the evidence for the phenomenon of epigenetics,
then define it, and briefly summarize epigenetic mechanisms.
Next, we will cover the epigenetic phenomenon of genomic imprinting, and finally,
we will discuss how environmental perturbations in
early life can result in disease later in life.
Identical, or monozygotic twins are derived from the same fertilization event, or zygote.
They have identical DNA,
but it is well-known that although they may be indistinguishable by sight,
they have variable susceptibilities for disease.
The next slide shows the disease susceptibility of
a variety of common diseases in monozygotic twins.
This slide illustrates the age at disease onset on
the x-axis and concordance rates of monozygotic twins on the y-axis.
The left and right margins of each shape represent the range of age at
onset and the upper and lower margins represent the
lowest and greatest concordance rates of each disease.
The data are taken from at least two independent twin studies.
Cleft lip and palate
occurs during embryogenesis and therefore, it is placed to the left of this graph.
As you can see,
there is an early age of onset and a high degree
of concordance for autism in monozygotic twins.
In contrast, breast cancer has a much lower degree of concordance,
suggesting an environmental component.
This environmental component is considered epigenetics,
which is defined in the next slide.