New Insights into the Nature vs.
Nurture Debate: Implications for
Child Health and Development
Sandra Daack-Hirsch PhD, RN
Associate Professor
The University of Iowa College of Nursing
http://www.theguardian.com/fashion/gallery/2014/aug/27/
gingers-scotlands-redheads-in-pictures#img-1
Does your DNA define you?
– What role does the environment and genetics play
in our likeness or differences with our siblings?
• Physical: on average we’re the same as our sibs
• Intellectual: on average we’re the same as our sibs
• Personality: less than 20% alike
•
•
Alex Speigel Interview Dr Robert Plomin
November 22, 2010 Morning Edition with Steve Inskeep.
Epigenetics
epi (Greek): on, above, in
addition to
The study of heritable changes
in gene expression without a
change in DNA sequence
http://www2.le.ac.uk/departments/genetics/vgec/schoolscolleges/epigenetics_ethics
Image taken from Felsenfeld
and Groudine (2003)
Controlling the double helix
Nature 421, 448-453
http://www2.le.ac.uk/depa
rtments/genetics/vgec/sch
oolscolleges/epigenetics_et
hics
Histone
tails
DNA
Image taken from Luger et al., (1997) Crystal structure of the nucleosome core particle at 2.8Å resolution. Nature 389, 251.
Turn
genes on
or off
0
F: turn
genes on
R: Turn
genes off
Turn
genes on
Turn
genes off
Epigenetics and disease
• Epigenetics provides the missing link on
how the environment can change the cell
without causing mutation to cause disease
• Studies have shown that modifications can
be passed down from generation to
generation and can be associated with
causing or predisposing disease in
offspring
Epigenetic Inheritance
Proving epigenetic inheritance is not
always straightforward. Researchers must:
•
Rule out the possibility of genetic
changes
In organisms with larger genomes, a
single mutation can hide like a needle in
a haystack.
•
Show that the epigenetic effect can
pass through enough generations to
rule out the possibility of direct
exposure
In a pregnant mother, three generations
are directly exposed to the same
environmental conditions at the same
time. An epigenetic effect that
continues into the 4th generation could
be inherited and not due to direct
exposure.
Maternal Smoking
http://teach.genetics.utah.edu/content/epigen
etics/
Epigenetic Inheritance
• Evidence for persistent
epigenetic differences
associated with
prenatal exposure
IGF2
methylation
– Dutch winter famine in
the WWII
Heijmans, et al. (2008) Persistent epigenetic
differences associated with prenatal exposure
to famine in humans. PNAS; 105(44). 1704617049.
Environmental changes
http://www.beginbeforebirth.org/
Epigenetic therapy?
• The epigenome is dynamic with the modifications
reversible. Because of this, it is possible to modify
the gene expression of cells.
– Using drugs,
– Altering the environment, and
– Changing behaviours…
• So that abnormal patterns become normal
Epigenetics and Society
• Will society demand a higher level of moral
responsibility to be placed on individuals to make
lifestyle choices that limit risk for preventable diseases
in themselves as well as future generations?
• Does epigenetics represent a “socially transmitted”
form of disadvantage that will emphasize the
responsibility of society rather than the individual in
addressing health needs.
• Will the potential loss of privacy of epigenetic
information lead to discrimination in employment and
insurability, emphasizing the need to amend the
current genetic-specific non-discrimination law?
Discussion and Questions