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Update – Applications of Genetic
Engineering
•The first drug produced in genetically
engineered animals was approved by the
Food and Drug Administration (FDA),
Feb. 6, 2009.
•GTC Biotherapeutics produces the human
protein antithrombin, a blood thinner,
under the name Atryn.
•Produced in goat milk
New York Times
More on Forensic DNA Analysis
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Touch DNA – in use for only about 5 years.
Needs only about 8 skin cells.
PCR used to copy 13 genetic locations.
These are highly variable; almost no chance
that two people will match.
• In 2008, used to clear the family of
JonBenet Ramsey in her 1996 murder.
Genomics
Part 2
Review
Genome all the DNA in one cell
of an organism
The Human Genome
• About 3 billion bp
• Current estimates are that the human genome
contains about 25,000 genes
• Only 1.5% of the genome codes for genes.
• The rest is involved in regulation, or is “junk.”
• The number of genes is not much different than
in many other “simpler” organisms.
Medical Applications
• Identification of human genes whose mutation plays
a role in genetic diseases
• Diagnosis of genetic disorders
• Understanding of cancer
• Understanding how your genetic makeup affects
your chances of getting cancer, heart disease, etc.
Diagnosis of Genetic Diseases
• Medical scientists can now diagnose hundreds of
human genetic disorders
• PCR can be used to copy a gene related to a disease in a
sample of a person’s DNA
• The copied DNA can then be sequenced to look for the
mutation that causes the disease
• Parents can be advised whether they carry diseasecausing genes
• A fetus can be tested to see if has disease-causing
genes.
Cancer Genomics
• In the past, scientists discovered several genes that
can cause cancer when they are changed.
• A new method to discover cancer genes is to
compare the entire genome of a cancer cell to the
genome of a healthy cell in the same person.
• In 2008 the first such study was reported, for a
woman with leukemia. 10 mutated genes were
found. 8 of these had not been known to be
related to cancer.
Personal Genome Project
• To determine genomes of individuals and compare
them to their medical information.
• Will help research connecting genes to health.
• Results will be made public.
• First 10 volunteers have been selected, and some
results have been released.
• Plan is to determine thousands of individual
genomes in next five years.
The PGP 10: The first 10 volunteers in the Personal Genome Project are currently having the
coding regions of their genomes sequenced; a small piece of sequence is shown for those whose
data is posted online. The sequence data will be stored in a public database, along with the
volunteers’ medical records and other information, such as their facial morphology (as measured
by the forehead tapes). Scientists will use the database, which is expected eventually to include
100,000 people, to search for links between genes and diseases or other characteristics.
Credit: courtesy of personalgenomes.org . Technology Review, Jan.-Feb. 2009
Personal Genomes
• The cost for an individual genome is now
between $100,000 and $1,000,000.
• One company promises a $5000 genome by
2010.
• Another predicts a $1000 genome by 2013.
Personal Genetic Testing
• Tests look at many genes linked to diseases,
or markers for different ethnic groups.
• May examine hundreds of thousands of
spots in your DNA (but not entire sequence)
• Take scraping from inside of cheek
(contains enough cells to give DNA for
testing), mail to company
Personal Genetic Testing –
Medical Applications
• Most common diseases are not usually linked to
just one or two genes.
• Instead, they may be caused by many different
genes.
• Some have only small effects.
• Some gene differences may have large effects, but
are so rare that they have not yet been discovered.
• Therefore it is difficult to get useful information.
Personal Genetic Testing –
Medical Applications
• Most common diseases are not usually
linked to just one or two genes.
• Example: at least 18 genes are
involved in type 2 diabetes.
Many Genes, Small Effects
Take height. Though health and nutrition can affect stature,
height is highly heritable: no one thinks that Kareem
Abdul-Jabbar just ate more Wheaties growing up than
Danny DeVito. Height should therefore be a target-rich
area in the search for genes, and in 2007 a genomewide
scan of nearly 16,000 people turned up a dozen of them.
But these genes collectively accounted for just 2 percent of
the variation in height, and a person who had most of the
genes was barely an inch taller, on average, than a person
who had few of them. If that’s the best we can do for
height, which can be assessed with a tape measure, what
can we expect for more elusive traits like intelligence or
personality?
Steven Pinker, “My Genome, My Self” (New York Times, Jan. 11, 2009)
Tracing Families
• As with personal genetic testing for medical
purposes, services look for many genes but do not
sequence all the DNA
• May examine:
o Autosomal DNA to examine genes inherited from all
ancestors
o Y chromosomes (passed on from father to son) to
determine family trees along the male line (usually the
same as last name); women can submit sample from a
close male relative.
o Mitochondrial DNA to look at the female line.
Tracing Families
• May find where your ancestors came from
and what ethnic groups they belonged to.
• Possible drawback: people may discover
that they are not related in the way they
thought (infidelity or adoption)
• Cost: $100 to $1000
“So if you are bitten by scientific or personal
curiosity and can think in probabilities, by
all means enjoy the fruits of personal
genomics. But if you want to know whether
you are at risk for high cholesterol, have
your cholesterol measured; if you want to
know whether you are good at math, take a
math test.”
Steven Pinker, “My Genome, My Self” (New York Times, Jan. 11, 2009)
Personalized Medicine
• Will target drugs to your personal genetic
profile
• Because they have differences in the
enzymes that get rid of drugs, different
people will respond best to different drugs,
or should have different doses.
• Some cancer drugs work best for certain
patients.
Personalized Medicine
Ethical Issue: Genetic
Discrimination
• Potential for employers to use genetic
information in workplace
discrimination
• Potential for health insurers to deny
insurance or charge higher rates for
people with risky genes
Genetic Information
Nondiscrimination Act (2008)
The Administration favors enactment of legislation to prohibit
the improper use of genetic information in health insurance
and employment. The Administration supports House
passage of H.R. 493, which would
• prohibit group health plans and health insurers from
denying coverage to a healthy individual or charging that
person higher premiums based solely on a genetic
predisposition to developing a disease in the future.
• The legislation also would bar employers from using
individuals’ genetic information when making hiring,
firing, job placement, or promotion decisions.
http://www.genome.gov/Pages/PolicyEthics/GeneticDiscrimination/SAPonHR493.pdf