On pages 68- 70
Dr. Maolem talks about a gene in the human body, CYP2D6 and how it can have a
major impact on the body. This relates to Big Idea #2, which states: Biological
systems utilize free energy and molecular building blocks to grow, reproduce,
and to maintain dynamic homeostasis; CYP2D6 is an important gene affecting how
the body metabolizes more than 25% of all pharmaceuticals. People who only have
very few copies of this gene are considered ‘slow metabolizers’.
Explain in detail
what the CYP2D6 gene is and does. Why are too many copies of this gene harmful
to the body? What are the advantages and disadvantages for having more or less
copies of this gene? Which chromosome is the gene located on? Is this a genetic
disorder? If so, explain what type of genetic disorder is it and how it affects
the allele frequency. Finally, explain what relation this gene has to Parkinson’s
disease and please cite a source.
Pranathi Merneedi (pmernee4@students.d125.org)
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ReplyDeleteOn pages 68 – 70 Dr. Maolem explains that research has proven that CYP2D6 is an example of a gene that affects our body based on how many copies of the gene occurs in our genome. As Dr. Maolem said, “it’s quantity and quality”. The official name of this gene is, Cytochrome P450 2D6. It is one of the most important enzymes involved in the metabolism of substances that are not originally produced by our body, such as drugs. The more copies of this gene, the quicker you metabolize the pharmaceuticals. While fast metabolization of the body is usually connotated with a positive outlook, the more copies of CYP2D6 can actually lead to death. Since this gene is directly related to metabolizing drugs, if the body metabolizes the drug too quickly, the drug which was actually harmless and supposed to help you, can easily become much more potent due to the fast conversion.
ReplyDeleteWhile there are many risks to having more copies of this gene, it is also important to realize that there are also a few advantages. As Dr. Maolem points out, people who happen to have many copies of the gene can detoxify harmful substances in the environment (68-69). Maybe in a previous environment, there were toxic plants and insects, and in order to overcome the barrier, those with many copies of the CYP2D6 gene survived. The environmental and selection pressure led to the favorable variation, more copies of the gene, to be selected for. Over time, after the population was well adapted, the population dispersed, which is now seen as a fraction in our large population today. 10% of Caucasians and 1% of Asians are said to fall into the category of fast metabolizers.
The number of copies of the CYP2D6 gene is not a genetic disorder, but it is autosomal recessive inheritance
(http://www.aruplab.com/Testing-Information/resources/TechnicalBulletins/Cytochrome%20P450%202D6%20(CYP2D6)%2014%20Mutations.pdf). This affects the allele frequency because you need both recessive alleles in order to have more copies of the gene; there is only one possibility of having more copies of this gene. Also, both parents must at least be heterozygous for the gene in order for there to be 25% chance that their children will have more copies of the CYP2D6 gene.
A very recent study shows that patients diagnosed with Parkinson’s disease have lower amount of the CYP2D6 enzyme in their brain. The enzyme CYP2D6 also inactivates neurotoxins. People with few copies of the CYP2D6 gene are at higher risk for developing Parkinson’s disease. The risk is higher when at exposure to pesticides. Compared to the Parkinson disease controls (in the experiment done), those who had Parkinson’s had approximately 40% lower CYP2D6 levels in the brain. In conclusion, the study had proven that lower CYP2D6 levels in Parkinson’s Disease cases may have reduced their ability to inactivate the neurotoxins that cause Parkinson’s, contributing to their disease risk http://www.ncbi.nlm.nih.gov/pubmed/21958961).