Dear Grandma,
I would love to assist you with all your doubts about the kit you are planning to use but let me first clarify in simple words some important biology concepts that are crucial to understand how the kit may work. One of the most important achievements of modern biology is that we are able to see whether we have a predisposition to a medical condition. The very molecule that stores information to replicate life, i.e., the DNA also has the ability to inform us about the possibilities to experience some sort of malfunctioning that would end up in a disease. The Human Genome project provided the complete DNA sequence of a human being (Witkowski, 2010). As a result, we now know that minute changes in that sequence might trigger different medical conditions. The project clearly demonstrated that groups of individuals experiencing diseases share a common alteration or mutation on their DNA sequences. This evidence encouraged researchers and pharmaceutical companies around the world to seek for a link between mutations and incurable diseases of high incidence and intensive care such as Huntington’s, Alzheimer’s, and Parkinson’s diseases (Witkowski, 2010). Not only some connections have been found but an incredibly large set of inexpensive state-of-the-art instruments and techniques (from 1,000 to 4,000 USD) have became available to the general public to determine whether a particular mutation is present in one’s DNA (Schneider, Schneider, & Klein, 2011). For instance, in the case of Alzheimer’s a variety of kits for genetic detection are available. This is particularly important for those whose relatives have suffered with the condition considering that an important fraction of Alzheimer’s cases are attributed to inherited DNA mutations (Jill S. Goldman, 2012; Roberts, Christensen, & Green, 2011). Most of the cases are attributed to mutations in the genes that encode for important proteins in the brain: Amyloid Precursor Protein (APP), Presenilin 1 (PSEN1), and Presenilin 2 (PSEN2). Proteins are tiny machines that conduct most processes in our body. APP, PSEN1, and PSEN2 are responsible for cutting and facilitating the disposal of toxic compounds (Jill S. Goldman, 2012). The mutations impede these machines’ proper functioning and as a result, the toxic compounds start to accumulate in the patient’s brain. The consequences of the malfunctioning are loss of memory and impairment of several cognitive functions. These symptoms are usually observed early in life and as time passes the patient experiences aberrant behavior and finally dementia. Carrying the mutation is not assurance for developing the condition; scientists believe that environmental aspects such as a cholesterol rich diet and the lack of physical exercise may be contributing factors. When a parent carries the mutation, there is a 50% chance of inheriting it, a percentage that could be even lower if the environmental factors are prevented (J. S. Goldman et al., 2011).
The dominancy of the inherited genes is a factor that defines whether a condition is going to be developed or not. In the case of Huntington's disease the inherited mutation is always dominant, which means that the altered information is going to be expressed in all situations. On the contrary, in recessive disorders two copies of the mutated genes are required to cause the disease. Scientists have coined the term penetrance to make reference to the number of individuals with a particular mutation who will develop the disease. For Huntington’s, the penetrance is virtually 100%, which means that every single individual will develop the condition. Penetrance changes according to genetic background (i.e., ethnicity) and environmental factors (Schneider et al., 2011).
Today, different types of genetic testing methods are available. Some are applied when the condition has been already developed while others are useful for predicting whether a person has genetic alterations that could potentially lead to a condition (J. Lloyd, n.d.). The second group of tests has been very controversial because of the impact it might have on patients. Some of the tests are now easily accessible in a direct-to-consumer manner without the need of passing through a conventional health care facility. Some people argue that this information could be potentially used by health insurance companies to limit coverage or simply refuse to accept an application. Additionally, there are some concerns about employers finalizing contracts to these people or even a complete dismissal of job applications (J. L. Lloyd, n.d.; Schneider et al., 2011). Other impacts include intensive stress, depression or even suicidal tendencies. In my opinion, companies should not be allowed to freely commercialize these tests considering that the legislation is not strong enough to support those who test positive. People may end up risking their financial stabilities and in the long run complete families may be under incessant scrutiny. Additionally, the general public needs to be educated in how to read the results considering that they generally exhibit an important level of complexity. The direct-to-consumer service for diagnosis generally includes blood or fluids withdraw that is in most cases conducted at home. This procedure may not be necessarily as rigorous as required to obtain robust data that supports the possibility for a life time condition.
I would prefer not to be tested for a condition such as Huntington’s disease. I am not particularly resilient to bad news and unfortunately my body tends to react negatively so I am very afraid of getting into a very depressive state of mind. I believe that in a condition where no cure is available, no matter you know about it your life is going to come to an end. So, it is better to have a peaceful and enjoyable life while the condition remains unexpressed. If for some reason I need to be tested for one of this fatal conditions and the results turn out to be positive, I would definitely choose not to have offspring. I believe that it is unfair to condemn your own descendents to a life of suffering and limited expectations.
References
Goldman, J. S., Hahn, S. E., Catania, J. W., LaRusse-Eckert, S., Butson, M. B., & Rumbaugh, M. (2011). Genetic counseling and testing for Alzheimer disease: Joint practice guidelines of the American College of Medical Genetics and the National Society of Genetic Counselors (vol 13, pg 597, 2011). Genetics in Medicine, 13(8), 749–749. doi:10.1097/GIM.0b013e31822dd062
Goldman, Jill S. (2012). New Approaches to Genetic Counseling and Testing for Alzheimer’s Disease and Frontotemporal Degeneration. Current Neurology and Neuroscience Reports, 12(5), 502–510. doi:10.1007/s11910-012-0296-1
Lloyd, J. (n.d.). Genetic testing: Does Kristen Powers have mom’s fatal gene? Retrieved from http://usatoday30.usatoday.com/news/health/story/2012-06-02/huntingtons-genetic-testing-followup/55345096/1?loc=interstitialskip
Lloyd, J. L. (n.d.). Genetic testing and disease: Would you want to know? Retrieved from http://usatoday30.usatoday.com/news/health/story/2012-04-09/genetic-testing-huntingtons-disease/54475708/1#.T9e3-dCAwCI.email
Roberts, J. S., Christensen, K. D., & Green, R. C. (2011). Using Alzheimer’s disease as a model for genetic risk disclosure: implications for personal genomics. Clinical Genetics, 80(5), 407–414. doi:10.1111/j.1399-0004.2011.01739.x
Schneider, S. A., Schneider, U. H., & Klein, C. (2011). Genetic Testing for Neurologic Disorders. Seminars in Neurology, 31(5), 542–552. doi:10.1055/s-0031-1299792
Witkowski, J. (2010). Long view of the Human Genome Project. Nature, 466(7309), 921–922. doi:10.1038/466921a
