Many human diseases have a genetic component. People may not know that they have a genetic defect that will lead to getting a disease and, in some instances, may have deliberately chosen not to know. Therefore when other people or organisations such as Police get this information, there are healthcare and privacy implications.

One such disease is Huntington’s disease (HD). It is fatal and has no cure. The US National Human Genome Research Institute notes that Huntington’s disease is an inherited neurological illness causing involuntary movements, severe emotional disturbance and cognitive decline.

A single abnormal gene produces HD. In 1993, scientists finally isolated the HD gene on chromosome 4. The gene codes for production of a protein called “huntingtin,” whose function is still unknown.

Since the gene that causes HD is dominant, each child of an HD parent has a 50% chance of inheriting the HD gene. The child needs only one copy of the gene from either parent to develop the disease. A person who inherits the HD gene, and survives long enough, will sooner or later develop the disease.  Symptoms of HD generally appear in mid-life.

Deciding to be tested for Huntington’s disease can be difficult. Individuals consider genetic testing to confirm a diagnosis when clear symptoms are present and there is a documented family history of HD. Others who have a parent with the disease elect to be tested to resolve uncertainty about their future. A negative test relieves anxiety and uncertainty. A positive test enables individuals to make decisions about careers, marriage and families.

Some who are at risk choose not to take the test. They choose to live with the uncertainty of being at risk and to forgo the emotional consequences of a positive result, as well as possible losses of insurance and employment.

DNA profiles are currently generated from points of the DNA sequence that do not reveal much sensitive genetic information. For instance the profiles do not reveal someone’s physical appearance, ethnicity or most inherited medical conditions. However, in theory scientists could deduce from a DNA profile whether a person has a defect related to certain diseases such as Down syndrome or Huntington’s disease – although they do not currently do so.