April 25 is National DNA Day, a day created to commemorate the completion of the Human Genome Project in 2003, and to commemorate the discovery of DNA's double helix structure. Today, we also celebrate the release of the total COW genome - see some great questions below from a local New Jersey high school.
Excerpted from: 2009 National DNA Day Moderated Chat Transcript
Q: American History HS in NJ (n/a grade teacher): HIV has proven to be a formidable enemy. How can our knowledge of DNA help put us a step ahead of the many mutations of this virus and allow us to conquer it?
A: Monica Alvarado, M.S., C.G.C.: One approach that may be promising is gene therapy. Clinical trials are under way to explore the potential for gene therapy as a treatment for HIV.
Q: American History HS in NJ (10th grade student): Can a trisomy like Down Syndrome, which is identified before birth, be corrected before the child is born so that he won't have the syndrome?
A: Don Hadley, M.S., C.G.C.: As you probably know, Down syndrome involves a person having an extra chromosome 21 in each and every cell of their body that exerts its effects from the time of conception.Therefore, trying to take that chromosome out would be essentially impossible early enough to make a difference. From a slightly different perspective, I would love to take away the medical problems people with Down syndrome experience, but I would not want to change them otherwise.
Q: American History HS in NJ (10th grade student): I am surprised that cows share so many genes with us. What other animals would I be surprised to find out have such commonalities? (Not including primates.) Stephanie Fisher
A: Praveen Cherukuri, Ph.D.: It all depends on the "degree of sharing" and how one defines "sharing". We share DNA sequence similarity in certain genes to varying degrees with a lot of living organisms. These genes in essence are critical for the maintenance of life. Although the similarity in genes is high (or low for that matter), one needs to be aware that, it is highly critical when (temporal) these genes are expressed and to what degree (levels of protein product) they are expressed.
Q: American History HS in NJ (n/a grade teacher): What is your position on companies who offer pet cloning services? Understanding that it is the DNA (and not necessarily Fluffy's amazing capacity for tricks) that is being cloned, aren't they taking advantage of a person's emotions?
A: Vence Bonham, J.D.: I believe it is helpful to have a basic understanding of the science, that will help individuals understand what it means to "clone" their pet. Learning science is important!
Q: American History HS in NJ (n/a grade teacher): We are in the middle of the 6th mass extinction. As we continue to map out genomes for various organisms, could there be hope for the next version of man to have the technology to 'repopulate' the planet with the amazing organisms that have become extinct?
A: Heather Junkins, M.S.: The idea of recreating extinct populations is highly controversial and needs further examination.
Q: American History HS in NJ (n/a grade teacher): Advances in technology and the understanding of DNA have enabled for the identification of genes that cause cancer and other diseases. How soon can we turn those genes 'off' so that once identified, they can no longer code for their particular disease.
A: Dawn Peck, M.S.: Many genes have been identified to play a role in cancer. They work in different ways. Targeted pharmacogenomic medicines will probably be useful sooner than turning genes off.
Q: American History HS in NJ (n/a grade teacher): Is there evidence or the potential for evidence on understanding or determining one's intelligence (or intellectual potential) by merely looking at their genes?
A: Eric Green, M.D., Ph.D.: Intelligence is a complicated concept, with many things contributing to one's intelligence (genetics, environment, nutrition, schooling, etc.). Genes play a role, but these other factors are critically important as well. Meanwhile, we really don't know know which genes are the critical ones, and there are likely hundreds or more that are relevant. In short, we are no where near being able to look at someone's genes and say anything intelligent about their intelligence.
Q: American History HS in NJ (n/a grade teacher): Somewhat silly question - now that we know that cows share 80% of our DNA (which is more than rats or mice) - will there be building of some seriously new larger labs to house cows as our new lab subjects?
A: Michael Dougherty, PhD: Probably not. Good model organisms for genetics must be inexpensive, easy to care for, and reproduce rapidly, and cows don't fit the bill. Still, the cow genome will allow cattle breeders to be more efficient with their selective breeding.
Q: American History HS in NJ (n/a grade teacher): Our classroom houses the Human Genome Landmarks poster which contains a picture of each chromosome with selected genes, traits and disorders - there are a ton of them! We're wondering how many were not included?
A: Donna Krasnewich, M.D., Ph.D.: This is a great question. As you can tell from your poster there are 23 pairs of chromosomes that carry the DNA of the human genome, 46 chromosomes total. The current thought is that there are about 20,000 genes in the human genome. We know what some of them do, others we don't. There is a wonderful data base on line, called the Online Mendelian Inheritance in Man, or OMIM, that details what we know about the genes. Check out this website for facts about the genome and disease http://www.ncbi.nlm.nih.gov/Omim/mimstats.html. This database tells us that there are over 12,000 genes with known sequence. 373 genes with a phenotype, or known clinical feature or disease associated with it. There are probably hundreds more where there is not quite enough data to fit into this category. In OMIM there are then listed diseases expected to have a genetic basis but scientists have not figured out which gene. There is plenty of work to do!
Q: American History HS in NJ (n/a grade teacher): I've just read that the cow genome has been completely mapped out. Was it a surprise to see that their total number of genes averaged only about 2,000 or so less than humans?
A: David Bodine, M.D., Ph.D.: That was no surprise. In fact, I think that as the cow genome is more worked out, we'll find a few more. When the first human sequence came out we were expecting a MUCH larger number of genes. Some of this was because there are a lot of proteins, but now we know that one gene can code for many proteins. The other reason was arrogance, if yeast and worms have 3-5000 genes, and flies have 14,000, the humans had to have many more. However, this is not correct. It is not haw many genes you have, it is how they work together that make a cow a cow and a human a human.
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