“I love her so much that I had trouble convincing myself that she had it,” said Dr. Young, who is an expert on the disease. “I would try to make it go away in my mind. And I think a lot of people did.”

But some colleagues bluntly asked Dr. Wexler if she had the disease. A few went so far as to tell her she did. She would say she did not, only to be told that denial was a symptom. If she happened to cross her legs, some accused her of trying to hide tremors. She found it infuriating.

Dr. Pardes warned the meddlers to back off. People learned to avoid the subject.

“It was always the big elephant in the room,” Dr. Young said. “It made everything uncomfortable for all her best friends, who just withdraw a little bit because they don’t want to hurt her.”

Her sister encouraged her to open up.

“I think that one thing her coming out about it will show is that getting a diagnosis of Huntington’s disease is not a death sentence,” Alice Wexler said. “It’s something people can live with for a long time, if they have the right medical care and social services. She has been living her life in a productive way, and still will.”

And so she is, reviewing grant applications, raising money for research and attending scientific conferences. Dr. Wexler holds out hope for the work on new drugs. There is still much to be learned, she says, and she still has a great deal of work to do.

“Enjoy life while you can,” she advises. “Find what gives you some pleasure and go for it. Don’t get kidnapped by this.”