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DNA Carrier Testing for Huntington’s Disease
Huntington’s disease is a rare condition that affects muscle control and causes eventual mental and behavioral decline. It begins with odd muscle stiffness and ambulatory trouble then progress into dementia. The loss of muscle control is characterized by jerky, rapid movements once known as chorea. As it begins to kill the nerve cells of the brain it often leaves its victims unable to speak or swallow correctly. Significant weight loss is a symptom at most stages of this disease and should be monitored carefully as it may lead to malnutrition. Most commonly diagnosed in middle age, Huntington’s disease can appear in children or young adults.
Huntington’s disease is not communicable. In order to have it, one parent must be affected. There is a fifty percent chance for every child from a couple where one parent has Huntington’s to be affected by the disease. It is a dominant gene and does not “skip generations.” If a person is carrying the abnormal gene known as huntingtin that person will exhibit symptoms and eventually suffer from every stage of the disease. Symptoms may vary with individuals, however, all people with Huntington’s will follow the same stages of movement, cognitive and psychiatric disorders.
Huntington’s disease is caused by an abnormal replication of the amino acid glutamine in a person’s DNA. In a normal cell, glutamine only replicates up to thirty-six times but in a person with Huntington’s, the amino acid continues replicating beyond that number. This abnormal amino acid was discovered in 1993 and today there is a number of DNA Carrier tests for Huntington’s disease available to anyone who wishes to take them.
A predictive genetic test first involves testing the blood of a family member, then the patient. Allowing the first test to be a family member helps rule out any genetic anomaly that would change the test result. This is a useful screen for anyone who is at risk long before they exhibit any symptoms of the disease.
Prenatal tests and newborn screening involve testing a blood sample for missing or abnormal genetic components and could be used to test for Huntington’s disease.
What can a DNA carrier test for Huntington’s disease tell me?
Preimplantation testing could be used by a couple where one or the other is positive for Huntington’s. It allows embryos to be tested prior to implantation to be sure they are not carriers of the disease.
Carrier tests only show whether a person is carrying the abnormal gene, not when symptoms will appear in their lifetime.
The ethical dilemmas and life choices that DNA Carrier testing for Huntington’s disease may bring about will certainly be difficult. However, there are many options available for at-risk people, genetic positive and caregivers. Since there are no known cures for Huntington’s, support groups and research facilities offer therapy and symptom management. As of July 2016, there is a bit of hope for sufferers of Huntington’s disease. The experimental drug Deutetrabenazine is said to help control involuntary muscle movements and when it is approved will be available for patients.