What’s in a Genome?
The sum total of the entire DNA in an organism is called a genome. Genomes are composed of a series of 4 chemicals known as bases, A, C, T and G which are considered to be the building blocks or the code of life – – We can make some headway into understanding our genomes by determining the exact order of the bases in a strand of DNA – Put simply, genomics is the decoding of all your DNA and this is done by a technique called DNA Sequencing.
Ok, so what? If we can decode and understand our genomes, what does this mean for us – how will this impact our lives today or in the future? In a series of posts, I wanted to share with you some ways in which genomics can impact us, on both an individual level and on a global population level. Granted, there is a long way to go in genomic research and for sure, we don’t know everything yet but with what we do know today there some real examples of the impact genomics is having.
One of the most important aspects of knowing our genomes is the potential impact it can have on our health and wellbeing by arming us with information to make medical decisions and lifestyle choices.
Predicting Susceptibility to Cancer
Currently this test is not used for routine screening of the population but only for those women with a strong family history of the disease. Many of you may be thinking – why would I want to know this information? Won’t this destroy my quality of life as I will be living in fear? The reality is, that the best chances of surviving many cancers, is when they are detected early. Knowing that you carry the harmful versions of these genes, can enable you and your clinician to make better medical decisions – like starting regular mammograms at 25 (10 years earlier than usual) and having cancer screening tests more frequently and taking preventative therapies. In some cases, tests like these can really save the lives of the women afflicted with these mutations.
Which Drugs Should I Take?
Another example where genomics has made a significant contribution in healthcare is in being able to select the right drugs or therapies for an individual. Whenever I am prescribed a drug, I want to know, how effective will the drug be? What is the correct dose for me? Will I suffer from side effects? Cancer drugs for example are known to have some of the worst side effects and they only actually work in a small proportion of patients. One report states that cancer drugs only actually work in about 25% of the patients that take them and yet the majority suffer from severe side effects. Before you took a cancer drug and had to suffer the side effects, wouldn’t you want to know if it would even work on you? The field of study, which defines how your genetic information can predict your response to a drug, is known as Pharmacogenomics.
Warfarin is a blood thinner often prescribed to people who are at high risk of blood clots. It’s really important to get the dose of this drug right for the patient, too much and the patient can bleed to death, too little and the patient will be at risk of clotting, heart attack or stroke. I share this information with my physician because people like me, with an increased sensitivity must be prescribed a lower dose to prevent bleeding. It’s amazing that I can have knowledge of this information and these risks before ever needing to take the drug. In this case, I can actually avoid trial and error medicine all together.
Dodging The Disease Bullet
How about the ability to avoid diseases all together? Many complex diseases like certain types of cancer, cardiovascular disease, obesity and diabetes may have genetic components to them, but your lifestyle and environment can have very strong influences on the outcome and maybe even delaying the onset or avoiding the disease all together.
Melanoma is a prime example of this. Melanoma is a skin tumor that is responsible for the most skin cancer deaths. Research has shown that exposure to UV light from the sun or tanning lamps hugely increases the risk of developing melanoma. If you were aware that you carry an increased genetic risk of developing this disease, wouldn’t you want to take measures to control or limit the environmental or lifestyle factors that can increase your risk? For Melanoma, there are some simple measures to take to avoid this like using high SPF creams every day on all the exposed areas of your body or avoiding being outside in strong sunlight, or wearing protective clothing.
Eliminating Disease From a Population
Another example of using genomic information to avoid disease, is in carrier screening for recessive disorders. There are a class of diseases that an individual can be a carrier of genetically, although not actually suffer from the disease themselves. Examples of these diseases are Cystic Fibrosis, Duchenne Muscular Dystrophy and Tay Sachs disease. If two people who are both carriers of the same mutation have children, there is a very high chance that one or more of their children could be afflicted. This is particularly prevalent, although not exclusive to, communities or cultures where Consanguineous or blood relation marriages occur (often first or second cousins).
A simple genetic test can tell you if you and/or your partner were carriers of mutations for these genes. Knowing this information in advance would enable you to make informed reproductive decisions. In the case of a couple where both are carriers of mutations for a specific disease; options such as assisted reproduction or IVF exist. During the IVF process, the embryos can be screened for physical or genetic abnormalities before being implanted. This is known as PGS – Pre Implantation Genetic Screening. The Ashkenazi Jewish community, are known to have been afflicted with many of these recessive diseases in their populations. However, through diligent screening programs, genetic counseling and assisted reproduction programs they have managed to reduce the incidence of a neurodegenerative disease known as Tay Sachs by 90%
Knowledge is Power
These are just a few examples of what genomics can do for you today. We are of course, a long way from understanding everything about the genome and the factors that influence it and we are learning more and more every day. However some things that we do know today, really can impact your health and wellness. When it comes to your genome, knowledge really is power.
In future posts I will share how Genomics is impacting us today in areas other than health and give you a view into the next frontiers for genomics …. stay tuned!
- Cancer Genomics: Special Issue Published By Genome Research (medicalnewstoday.com)
- What will the $1000 genome do for you? (3quarksdaily.com)
- Have your own genome decoded – for just £650 (independent.co.uk)
- Know Thyself, Today. (bioneering.wordpress.com)
- From genomic data to new cancer drug (eurekalert.org)
- Gene survey: Do you want to know your future diseases? (genome-engineering.com)
- Cancer is just as deadly as it was 50 years ago. Here’s why that’s about to change. (io9.com)