1 in 20 Caucasians as carriers of the cystic fibrosis mutant allele equates to 5%. With 5% carriers, there is a probability of (1/20) X (1/20) = (1/400) that both parents will be carriers, and then a probabality that (1/2) X (1/2) = (1/4) that both carriers will pass on the mutant allele associated with cystic fibrosis. Therefore, the overall probability of cystic fibrosis disease is approximately (1/400) X (1/4) = (1/1600), which is approximately 0.0625%.
Approximately 1 in every 20 Caucasians are carriers for the mutant allele that causes cystic fibrosis. From this probability of carrier frequency, calculate the expected percentage of Caucasians to actually have cystic fibrosis.
The Recombinant DNA Advisory Committee has recently finished investigating gene therapy’s role in the death of 36 year-old Jolee Mohr who had received a protein-based drug called Enbrel that uses the tumor necrosis factor (TNF) for treatment of rheumatoid arthritis. The DNA vector used by the TNF protein is called an adeno-associated virus or AAV that is injected into the infected site to provide the TNF to the defective genes.
The concern with Mohr’s death is possibly attributed to the TNF protein that could have potentially caused the vector to multiply out of control leading to a fungal infection, which compromised her immune system. After her second injection, she was brought to the hospital with flulike symptoms caused by the infection with Histoplasma capsulatum, a common fungus, which was found in many of her vital organs.
Mohr was also taking a drug known as Humira which blocks the tumor necrosis factor (TNF) and ultimately suppress the immune system. The protein produced by the gene therapy is also a TNF-blocker; therefore, the combination could have potentially made her vulnerable to the fungal infection.
Another potential cause was a reaction to the gene therapy vector, adeno-associated virus. Vector DNA was found in low amounts in other tissues, illustrating the vector did not multiply. There is no definitive evidence that disproves the vector as contributing to her death, but it did not actually cause her death.
The Recombinant DNA Advisory Committee announced after intense investigation that it was not the gene therapy that caused Mohr’s death, and the ban was lifted on Enbrel’s use to treat arthritis.
The company responsible for the gene therapy trial is continuing with the trial study, but has increased its monitoring of patients. Those patients who have a fever, as Mohr did, will not be given the second injection.
1.What genetic information would you most like to know about yourself?
If I had to know something, I would want to know what possible genetic conditions I could prevent. For example, if I had a higher chance for heart disease, it would be beneficial to know so that I could exercise more and have a better diet in order to do everything I could possibly do in order to prevent the disease. I believe in preventative measures that could build a strong defense against those conditions that can be stopped before they occur.
2. What genetic information would you least like to know about yourself?
I would not like to know if I would be more susceptible to diseases that cannot be prevented. Knowing that I could get a disease such as Huntington’s disease, which cannot be prevented, I would hate knowing that I would die eventually and constantly living in fear of death. This would be hard to deal with knowing I am going to die but not knowing when it would happen. This is a scary thought for me, and I would not like to be plagued with trying to fight death so much that I forget to live to the fullest.
3. Would you be more interested in learning about your ancestry from your DNA or learning about your health from your DNA?
I would be interested in learning both because I think it is important to know both about ancestry and health. Ancestry would be beneficial in that I could learn about where my early ancestors originated. Ancestry can also play into learning about what genetic disorders often affect certain ethnic backgrounds. I would also be interested in learning about my health because it could help motivate me to have better exercising patterns and dietary needs in order to prevent the onset of certain diseases.
4) What aspects of genetic information should be public? What aspects should be private? What tests should not be allowed at all?
All aspects of genetic information should be private because it is an infringement on personal rights to have this information made public. If the information was made public, insurance companies could potentially charge more or not even insure those who have higher risks for diseases. Companies could also use the information to prevent hiring people because of certain ancestral backgrounds or because of specific genes. This information should be completely private. I do not think tests that allow for the “perfect baby” should be allowed. I do not think people should get to design what their babies should look like. That is a natural process that should be allowed to take its own natural course.
“PlasmID: A Centralized Repository for Plasmid Clone Information and Distribution”
Dongmei Zuo, Stephanie E. Mohr, Yanhui Hu, Elena Taycher, Andreas Rolfs, Jason Kramer, Janice Williamson, and Joshua LaBaer
The Plasmid Information Database was developed in order to establish a worldwide resource to initiate the search and request of plasmid clones with the Dana-Farber/Harvard Cancer Center DNA Resource Core. The website for PlasmID (http://plasmid.hms.harvard.edu) is a data storehouse that allows researchers to search the collection of plasmids online using gene names as well as defining characteristics such as vector factors and key aspects of the plasmids. As of 2006, PlasmID contains more than 46,000 plasmids in 98 different vectors. These plasmids are useful for cutting techniques and gene collections of various organisms. The plasmids are stored in -80°C freezing systems in order to preserve the clones. In order to prevent human error, this system is automated so that clone replication and distribution is monitored and maintained. This important website is crucial to the future of plasmid cloning so that researchers can use the vital information to make new discoveries in the world of genomes.
To read the entire article go to: http://nar.oxfordjournals.org/cgi/content/full/35/suppl_1/D680#SEC4
Here is the answer for the previously posted example exam question:
First you draw a circle in which there is one site for Xhol(1). Then the next site is for Xhol(2) with 2000 bases in between the two sites. Finally there is a site for Sall 500 bases away from the second Xhol(2) site. Therefore, that leaves 2500 bases between the Sall site and the first Xhol(1) site.
Sorry I couldn't draw the actual circle for you. Good luck studying for the exam!
While working with DNA sequencing, you study a tube containing plasmid DNA. You are studying the plasmid so that you can draw a map of the plasmid showing the relative positions of recognition sites for the restriction enzymes XhoI and SalI. You perform three separate reactions, mixing your plasmid DNA with: 1) XhoI alone, 2) SalI alone, and 3) XhoI and SalI together. You separate the products of these reactions by gel electrophoresis, with each of the three reactions in a separate lane on the gel. The gel tells you that the reaction with SalI produced a single DNA fragment of length 5000 bases; the reaction with Xhol produced two DNA fragments of length 2000 bases and 3000 bases; and the reaction with both XhoI and Sall produced three fragments of length 500 bases, 2000 bases and 2500 bases.
Draw a map of the plasmid showing the relative positions of the Xhol and SalI sites, and the distance in the bases between these sites.
Legs, Eyes, or Wings--Selectors and Signals Make the Difference
Markus Affolter and Richard Mann
This article is very useful in order to see how genes work in that it shows the experimental results of studies done on the fruit fly Drosophila melanogaster. This article discusses the variations of body plans of specific organisms as seen through specific genes. The scientists that led this experiment focused on selector genes that encode transcription factors that control the development of sets of cells that give rise to specific structures in the adult organisms. To build specific structures such as a leg or wing in the fruit fly, the cells also need to know where these structures should be located in the adult organism. This is accomplished through small sets of intercellular signaling pathways. In order to activate the transcription factors, a signaling effector is necessary to tell the cell which signaling pathway to use so that the specific structures can be produced. The interaction between the selector and signaling protein complexes are vital so that specific responses can be made to create structures such as wings, antenna, legs, and eyes in the Drosophila melanogaster. This article is important in showing the various intercellular processes that are necessary for genes to undergo so that organisms can have the right structures needed to become an adult.
To read the entire article, go to: http://www.sciencemag.org/cgi/content/full/292/5519/1080
Sidestepping Mutational Meltdown
Eric A. Shoubridge and Timothy Wai
Shoubridge and Wai present the fascinating results of an experiment in which mouse mitochondrial DNA with severe mutations is not passed down to later generations. The mitochondrial genome codes for important protein components of the organelle’s respiratory equipment as well as transfer and ribosomal RNAs. The first generation germ cell with severe mutations in the mitochondrial DNA is either destroyed by autophagy, in which the cell decomposes its own components, or through selection during the replication process. Therefore, the mature cell no longer has the mitochondrial mutation. The mystery as to why this occurs is still unsolved. This could be useful for explaining how mutations occur in genes and DNA. It would also be interesting to investigate specific instances when mutations are no longer transferred in later generations and the possible reasons why this occurs so that a deeper understanding of how genes work is reached.
To read the entire article, go to:
http://www.sciencemag.org/cgi/content/full/319/5865/914?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=genome&searchid=1&FIRSTINDEX=0&issue=5865&resourcetype=HWCIT
URL: http://blogs.nyu.edu/blogs/ams799/amanda1004/
School and Year: CAS Freshman
Major: Journalism and Communications
About Me: I am from New Orleans, which is a close second to New York City for the best city to leave in! I really am enjoying this class so far, and I look forward to learning more about genomes.