Genetic Testing

by on April 7, 2010

As genetic tests are developed, more and more of us are being offered knowledge about our medical futures.

In The Find,  Anna Silowski, an intense,  ambitious  paleontologist at the peak of her career  struggles with that choice, and in the process finds herself inextricably involved in an ‘impossible’  relationship with school-drop out  Scott MacLeod – a relationship which,  against all odds,  transforms both their lives.

Would you  chose  to know your medical  future, the possibly devastating information coded in your genes?

Many of us  assume that if we were at risk we would like to know the facts. Yet most people in this situation still chose not to test.  Since there is no cure – and very little treatment – knowledge, here, is of dubious value, and that value depends on both circumstances and personality. Here, Charlotte Raven writes with great clarity about her own experience of testing for Huntingdon’s Disease.

http://www.guardian.co.uk/society/2010/jan/16/charlotte-raven-should-i-take-my-own-life

Here is another account:

http://www.nytimes.com/2007/03/18/health/18huntington.html?pagewanted=6&ei=5090&en=7ce9d3291eab0b28&ex=1331870400&partner=rssuserland&emc=rss

About one in 10,000 people in the US, Canada and UK have HD,  a disease which affects not only the sufferer, but also his or her entire family.  HD research is ongoing, and at a crucial stage. For further information, and if you wish to donate, here are links the HD  Societies in Canada, the UK and the US

http://www.huntingtonsociety.ca/english/index.asp

http://www.hda.org.uk/

http://www.hdsa.org/about/our-mission/what-is-hd.html

Huntington’s is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.  The child of a person with Huntington’s has a fifty percent chance of inheriting the disease.
The gene for Huntington disease is found on the fourth chromosome. A chromosome is composed of genes, and each gene is composed of a string of molecules called nucleotides. The nucleotides are adenine (A), cytosine (C), guanine (G), and thymine (T). The gene is made up of a series of three nucleotides which form the structure of DNA in the gene. Each gene has its own unique sequence of base pairs. In Huntington disease, the DNA sequence, CAG (cytosine-adenine-guanine), is part of this sequence. This sequence (called a “trinucleotide repeat”) may be duplicated up to 26 times in the general population. People with Huntington’s Disease may have from 40 to over 100 repeated CAG segments.
The increase in the size of the CAG segment leads to the production of an abnormally long version of the huntingtin protein. The elongated protein is cut into smaller, toxic fragments that bind together and accumulate in neurons, disrupting the normal functions of these cells. The dysfunction and eventual death of neurons in certain areas of the brain underlie the signs and symptoms of Huntington disease.
We do not know exactly how the repeated sequence causes Huntington disease, but research to develop therapies to treat Huntington disease is ongoing.

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