Prof Young, who heads the department of neurology at Boston's Massachusetts General Hospital/Harvard Medical School, was a key member of the team which initially mapped the location of the gene for Huntington's disease.
She believes there will eventually have to be laws to prevent genetic discrimination of any kind.
Prof Young says it is not ethical to pressure people into behaving in certain ways because of genetic predictors.
There were all sorts of ways genetic information could be abused, including by the insurance industry.
The decision about whether a person wanted to know about their genes was an individual one and it was up to clinicians to help people understand the issues.
In the case of Huntington's, where the disease does not usually reveal itself before someone has reached their mid-30s, the Huntington's community advocated very careful education and counselling for people before they were tested.
Issues could include survivor guilt, where a family member might be found not to have the disease but siblings did.
Prof Young recalled the case of a man who demanded to have his two sons tested and when asked why, he explained he could only afford to send one to university.
That was the wrong reason to be tested, she said.
Prof Young, who has been in New Zealand on the Freemasons Roskill Foundation lecture tour, was in Dunedin recently to visit the University of Otago and deliver a lecture discussing recent advances in the understanding and treatment of Huntington's and Parkinson's diseases.
Caring for patients with both diseases over the past 30 years had been a driving force for her research into these conditions, she said.
"When you help someone through an illness over 20 to 30 years, you know that person very well. By the time the end comes with Huntington's disease, individuals still know who you are and that you're their doctor. Emotionally, it is very hard."
She also knew the effect both diseases had on family and friends.
Among the therapy developments in the field were work being done by Prof Richard Faull, a former University of Otago graduate now at the University of Auckland, involving the brains of sheep with Huntington's, work Prof Young described as " really spectacular".
Previous work had been done on mice, but the sheep brain was about the same size as a human's.
Working with sheep would allow further research into therapies which might reverse some of the symptoms, allowing people with Huntington's to stay in "a very functional state" for the rest of their lives.
A Parkinson's disease development showing promise was one which involved uric acid. It had been found in a study over three or four decades that unusually high levels of uric acid, commonly associated with gout, slowed the progress of the disease, but only in men.
It appeared that higher than usual levels of uric acid, even if they did not cause gout, could be beneficial. A drug trial associated with this finding was beginning at the end of this year.
That discovery was completely unexpected, Prof Young said.
It was an exciting time to be involved with research into both diseases. If therapies could be developed to slow down the diseases, there was more reason to believe that eventually something would stop them, she said.
"It's almost like Aids therapy. The first drugs that came out worked a little bit, then the next ones worked a little better until now the therapies allow people to live almost a normal lifespan."
It was always important for scientists to be open to the unexpected and remember the adage that luck came to the prepared mind.
"When we began, we had no idea where we were going. We were wandering around in the dark . . ."
Often it was the experiments that did not turn out the way the scientist might have wanted that were the best ones.
" You can't get too wound up in your own theories. If you try to force data into your own ideas, you're going to miss a whole lot of interesting stuff.
You've got to let your mind wander a bit," Prof Young said.
> Neurological conditions
Huntington's disease
• An inherited progressive neurological disorder.
• Disease characterised by marked involuntary movements.
• Eventually patients become totally incapacitated and mute, although the brain remains aware.
• A child has a 50/50 chance of inheriting the gene from an affected parent.
• Symptoms usually appear between the ages of 30 and 50.
• More than 600 families in New Zealand are affected by it.
Parkinson's disease
A progressive neurological condition.
• It has three main symptoms: tremor, stiffness and slowness of movement.
• It occurs when insufficient amounts of the chemical dopamine are produced by the brain.
• It affects about one in 500 people.
• About 1% of people over 60 have Parkinson's.
• With good medical treatment, it has a limited effect on life expectancy, but is disabling.
