Role of Genetics in
Alzheimer’s Disease
“Every man's memory is his private literature,” Aldous
Huxley….but not for people with Alzheimer’s disease. This slow progressive
crippling and severely damaging genetic disease is the number one killer for
our aging population of 65 and older. Alzheimer’s is the worst case of dementia
and eventually causes complete loss of brain function. Genetics is the basis,
the cause, and the answer to Alzheimer’s with billions of dollars being spent
on research. Scientists and academics have made many recent discoveries about
this widespread and debilitating disease.
Causes
Basically, Alzheimer’s happens when an overabundance of
beta-amyloid protein clusters and tangles of tau protein strands cause a loss
of connection with the synapses (transmitters between brain cells). Between these two toxic brain proteins, it
then causes inflammation, severe tissue shrinkage and eventually the death of
brain cells.
Early and Late Onset
At the National Institute of Aging, John Hardy, PhD,
researches and studies the roles that genetics plays in Alzheimer’s. On the
Alzheimer Association’s website, Hardy goes on to explain in a video, that it’s
a “complicated disease because they still don’t know the order of what happens,
so they can get to the beginning of the disease.” “…like what gene mutations
occur to create the disease.” The two
forms of Alzheimer’s are early onset and late onset.
Early onset is known to have a “rare genetic mutation,” from
one of four genes: Amyloid precursor
protein (chromosome 21), Presenilin-1 (chromosome 14), Presenilin-2 (chromosome
1), and Apolipoprotein-apoE4, (chromosome 19). The apoE4 is the “model
susceptibility gene.” This gene that
also gives us high cholesterol, also puts us at the greatest risk for
Alzheimer’s, and although we all have it, it doesn’t mean we are at risk for
the disease. There is approximately a ten percent chance of developing this
disease with no family history.
Late onset, as Hardy, puts it, “ …is much more puzzling and
hard to figure out.” Both environment
and susceptibility genes play a part. Dr. Hardy and associates are leading
genome-wide association studies to identify all the possible genes that may
play a role in this onset. What’s really
amazing is they now have the ability to place people’s DNA on a slide under the
microscope, and chip over five hundred thousand to a million sites, to help
decide what drug targets to develop to help fight the disease.
Link Between…
Another discovery I found really interesting was the
connection between Down Syndrome and Alzheimer’s. In a grants release from the, Global Down Syndrome Foundation,
they stated, “According
to the U.S. Centers for Disease Control, Down syndrome occurs in 1 out of 691
infants in the United States and is caused by inheritance of three copies of
chromosome 21.” It goes on to say, “People with Down syndrome develop the two
hallmarks of Alzheimer’s disease – Amyloid plaques and tau tangles – in their
30’s and 40’s.” The connection is believed to be, “…due to the extra copy of
chromosome 21, which contains the gene that encodes the amyloid precusor
protein (APP).
Never
Give up Hope
The most
frustrating part about Alzheimer’s is not being able to pin down a starting
point to find a complete cure. But I believe with how fast and far advanced
research has come in the past five to ten years alone, there is no doubt that
they will find a cure…and probably within our own lifetime.
References
HBO
Documentary Films with National Institute on Aging at the National
Institutes of Health in association with the Alzheimer's Association (Producers). Retrieved (2013,
March 10).
"THE ALZHEIMER'S PROJECT."
Video
retrieved from
http://www.alz.org/research/science/alzheimers_disease_causes.asp#genetics
The Alzheimer's Association. (2013). A closer look at genes linked to Alzheimer's.
Retrieved from http://www.alz.org/research/science/alzheimers_disease_causes.asp
Call, E.
A., Frantz, N., (November 29, 2012). Grants release
Retrieved
from http://www.alz.org/dementia/down-syndrome-alzheimers-symptoms.asp
Genetic Science Learning Center (2012, August 6).
Alzheimer’s Disease. Learn.Genetics. Retrieved March 13, 2013, from
http://learn.genetics.utah.edu/content/disorders/whataregd/alzheimers/
PART II
- What one assignment or activity you performed in this unit are you the most proud of?
I am really proud of myself for doing such a great job on
the flip a coin lab. It took me some time to figure out the flip a coin lab,
but once I got it, it was easy and interesting. I now have a better
understanding of how gene work. To me, it's mind boggling realizing how many
different variations of trait combinations they are!
- What do you now understand best about the information in this unit?
I have a more in depth knowledge of
genetics in general, cloning and use of the Punnett square. I never thought I
was going to understand how the Punnett worked with the different alleles but I
finally got it--just like a math problem. Ha! Learning about the DNA cloning
was not as tough as I thought it was going to be.
- What actions did you take for yourself to enhance learning or enjoyment of the material?
I watched a lot of videos online and
did a lot of my own research to get more in depth understanding of the
material. I also had a friend of mine, who is really good at genetic problems
help me to understand my genetics lab better with the Punnett square
problems--she was a big help.
- When did you feel most “connected” with the course? Most distanced?
I felt most connected to course when
I was understanding and studying about cellular reproduction. It is just so
fascinating to me how complex our human bodies are and delicate and intricate
our cells are and how they work. To think that they are millions of cells
within each of us are they are all performing differently and sometimes simultaneous
tasks at the same time is quite extraordinary. The most distance felt, was when
I was first frustrated with the flip-a-coin-lab and trying to grasp the
directions and couldn't get the one video you had recorded on it to work. I
know you kept trying and eventually I got it figured out and all was well! :-)
- What could I offer you to help your understanding or enjoyment of the material?
You are such a big help with all the
videos you make and send to us each week--you have no idea. The more the
better--although sometimes I don't have time to watch them all, it's nice to
have the options there. I really don't think I would have been able to pass
this course without them. Also really appreciate you responding so quickly on
the email. I know you have a lot of students to work with--it's very
appreciated. Please keep doing what you doing--it seems to be working for most.
