Opinion | Who Gets Left Behind When a Disease Is Cured?

Tyler Parish thinks of himself as “the last dinosaur.”

If he had been born decades earlier with the same genes, he would not have had access to the medical care and technology that allowed him to see his 43rd birthday.

But if he were born today with access to gene therapy for spinal muscular atrophy, he might have been able to walk without assistance. He might have been able to live a life without fear of impending medical catastrophe. He would likely not be in a long-term care hospital in Boston, with a team of doctors trying to decide whether he needs a tracheostomy tube and a ventilator at night for the rest of his life.

The way Mr. Parish sees it, the life he has lived will one day become something of a historical curiosity. His experience of S.M.A., with all the suffering it has entailed, will likely be rendered extinct.

Gene therapy has seen remarkable and highly publicized success in recent months, from the Food and Drug Administration’s approval of what amounts to cures for sickle cell disease to the news that a boy with congenital deafness could hear for the first time in his life following gene therapy.

These stories are, unsurprisingly, the ones in the headlines. But as science moves forward, there are an increasing number of people like Mr. Parish. There are life-changing treatments available for his disease, but they seemingly cannot reverse the damage that has already been done. A growing population of patients is faced with a challenging question: What is it like for those who know that their disease could be cured or significantly managed within their lifetime but that they won’t be able to — or might choose not to — see that benefit?

“When I talk as someone who is older, who is ‘missing out’ on some of these things, it’s not from a bitter place. It’s from a place of, ‘Thank God that these younger people are born at the right moment in time,’” Mr. Parish told me. “I love the idea that a kid can be born with S.M.A. and never know the infinite desperate medical situations, the social situations they’re going to be able to avoid.”