notes that, after mapping the human genome,
researchers wondered how so few genes could account for so much diversity among
the species.
recounts how one scientist determined how the
deletion of a key sequence of DNA on human chromosome 15 could lead to two
different syndromes depending on whether the deletion originated from the
mother or the father.
explains that this was the first human evidence
that something other than genes themselves could determine how genes are
expressed.
provides an animation of two ways that scientists
think the epigenome works to turn genes on and off.
cites differentiation as an example of the
epigenome at work—during development, cells switch on or off to
differentiate cell function; as the cells divide they retain a memory of their
cell type.
notes that while the epigenome is normally
incredibly stable, epigenetic switches sometimes can be thrown and later lead
to disease.
looks at how the epigenetic profiles of two
66-year-old twins are very different from that of two 6-year-old twins,
suggesting that epigenetic changes accumulate over time.
presents several experiments with rats that reveal
how the epigenome works in an animal model.
reports how epigenetic changes may promote disease
by silencing tumor suppressor genes or activating oncogenes.
reviews a clinical trial in which half the patients
recovered after being treated with a drug designed to remove chemical tags
silencing tumor suppressor genes.
presents the work of two scientists looking for an
epigenetic influence on autism.
reports on a review of generations of historical
records from a remote Swedish village that suggests epigenetic changes may be
passed down through the generations.
NOVA explores how the epigenome—the body's complex chemical
network that controls gene expression—plays
a role in human biological destiny.
