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Gene testing
Gene testing

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1.1.5 Late-onset single-gene disorders

An individual might know that a late-onset disease such as Huntington's disease (HD) is present in their immediate family and that they might have inherited the disease gene(s). The problems of genetic testing for HD revolve around the fact that it is pre-symptomatic.

One dilemma is the long delay between testing positive and developing the clinical symptoms of the disorder in middle age. Is it better not to know and live in hope, or as one victim cried ‘get it over, I'm so tired of wondering?’ Of course, a negative test result (i.e. the person does not carry the gene for HD) could be a huge relief, but for those who are told that they do carry the HD gene, there are huge psychological and practical problems.

One of the core issues in adult testing for single-gene disorders such as HD is getting informed consent from the patient to carry out the test. One problem is what counts as ‘informed’. How much does the patient need to know about the science of genetics to make a considered decision concerning a genetic test? But there are also examples of attempts to procure a genetic test for HD without the knowledge of the patient concerned. Sometimes this involves getting children tested, but cases have been reported where psychiatrists, social workers and lawyers have tried to get a test carried out on an adult without the permission of the person concerned. There can also be strong pressure on individuals who, although they are aware they are undergoing testing, might not be exercising their own best judgement. An example is the family pressure that can force prospective parents to be tested so that they can make ‘responsible’ decisions about having children.

A related problem is that even though someone may opt out of testing for HD, they may unwillingly discover their status through a member of their family going for a test.


Within a family, who do you think should be told the results of a genetic test and why?


There is no right answer here.

Do the individual's brothers and sisters have the right to information that relates to them? If a parent knows s/he is at risk and refuses to get tested, how would they feel if their adult son goes for a test for his own peace of mind and finds out he (and therefore his parent) carries the gene? Genetic information tells us about our families, whether we want to know or not.


Outside the family, who might be interested in the results of the test?


Employers and insurance companies.