reply to post by FissionSurplus
….although Down Syndrome is a DNA mutation, I believe that Alzheimer's is caused by environmental poisoning. What is the link?
Good question. …Both diseases involve mutations in the amyloid protein (as do other diseases) - in Down's, the protein mutation results from a gene
mutation, but in most Alzheimer's cases, the protein mutation is "sporadic" and epigenetic, not genetic.
In simple terms, epigenetic diseases involve mutated proteins, which can be inherited, but which do not involve DNA mutations, while genetic diseases
result from actual gene mutations. Down's is accepted as genetic, but some researchers are looking at the role epigenetics might play in Down's -
other researchers are looking at cases where Alzheimer's may be transmitted genetically rather than epigenetically or acquired (direct infection).
One of the better known mechanisms of epigenetic change is the prion - well-recognized as causing disease that is sporadic (epigenetic changes caused
by environmental trigger), familial (inherited either epigenetically or genetically), and acquired (known environmental source of infection).
Prion diseases are unique transmissible neurodegenerative diseases that have diverse
phenotypes and can be familial, sporadic, or acquired by infection. …
[It appears that some (many?) diseases start out as environmentally-induced epigenetic disorders, before modifying DNA and becoming genetic if they
are deemed "successful."
NOTE: Epigenetic changes seem only to become permanent (modify DNA) if there is a clear beneficial effect in evolutionary terms.
ALSO NOTE: Prion-related disease is currently defined as only neurodegenerative however, cutting edge research is looking at the paths prions take to
get from the gut or other points of entry to the brain, and at other diseases they may cause along the way.]
Professor Benjamin Tycko "Epigenetics and DNA methylation in Down syndrome"
Roger Reeves: Mouse models of epigenetics
Dr. Reeves studies specific changes in the craniofacial skeleton that are largely responsible for the characteristic facial appearance in Down
syndrome and contribute to sleep apnea and other clinical presentations. The Reeves laboratory has traced these changes to the cells of origin, the
neural crest. He is helping the Feinberg lab test its stochastic epigenetic plasticity model in mice, and he is working with Dr. Reddy on
nuclear structure in Down syndrome.
More on epigenetics.
EPIGENETICS AND INHERITANCE
We used to think that a new embryo's epigenome was completely erased and rebuilt from scratch. But this isn't completely true. Some epigenetic tags
remain in place as genetic information passes from generation to generation, a process called epigenetic inheritance.
Epigenetic inheritance is an unconventional finding. It goes against the idea that inheritance happens only through the DNA code that passes from
parent to offspring. It means that a parent's experiences, in the form of epigenetic tags, can be passed down to future generations.
As unconventional as it may be, there is little doubt that epigenetic inheritance is real. In fact, it explains some strange patterns of inheritance
geneticists have been puzzling over for decades.
edit on 2/3/12 by soficrow because: (no reason given)