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

• 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.

GenomicsGenomicsPart 2Part 2

Review

Genome all the DNA in one cell of an organism

• 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.

The Human Genome

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 disease-causing 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

ancestorso 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