Knox Singleton, the longtime CEO of Inova Health System, is pictured at his offices on Wednesday, September 27, 2017, in Falls Church, Va. (Jahi Chikwendiu/The Washington Post)

Knox Singleton envisions a time when health care is more focused on prevention than treatment. When genes will accurately predict illness and doctors are incentivized to keep patients well.

But after 35 years building a multilayered health-care system in Northern Virginia, Singleton will step down as chief executive of Inova Hospital System next year to cede space for the next leader to shape that future.

“You wouldn’t pick someone like me for the next decade,” he said during a recent interview in his Fairfax office. “I’ve done a reasonable job of getting us here, but if we want the second stage to kick in . . . I think it would be someone with a deeper appreciation of the science, the research and more of the clinical knowledge of how these new systems are going to evolve.”

Singleton was 34 years old and from a small Appalachian town in North Carolina when he arrived in Fairfax County in 1982 to oversee operations of three nonprofit community hospitals with about 1,000 employees in a county of about 650,000 people. A year later, he was promoted to chief executive.

At 69, he is now twice that age, and Fairfax has doubled its population. And the modest hospital system he inherited has evolved into a $3.5 billion enterprise with 17,000 employees.

He’s not especially nostalgic when he reflects on his tenure and instead looks forward, describing his aspirations for America’s health-care system and where, after all these years, it still falls short.

Singleton entered into the health-care industry accidentally. His father owned a hardware store and an insurance company, so Singleton assumed he, too, would work in insurance. But as a college student during the late 1960s, he became swept up in the national fervor to pursue an interest larger than oneself.

As a senior business major at the University of North Carolina, he was offered two opportunities post-graduation. He could move to Uganda with the still relatively-new Peace Corps or work in the administrative offices of a Cleveland hospital.

He said he often jokes that he chose the more “exotic” option and moved to Ohio.

Health care “melded the purpose I was looking for when I was all about the Peace Corps and wanting to do something good in the world, with the skills in business I had learned in my education,” he said. “And I never looked back.”

During his years running Inova, the hospital system performed the metro area’s first successful heart transplant in 1986 — the woman is still alive; established specialty hospitals like Inova Women’s Hospital and Inova Children’s Hospital; created clinics for low-income patients; and developed the Inova Schar Cancer Institute — a research hospital Singleton hopes will one day be on par with the esteemed Mayo Clinic.

But he’s most excited about Inova’s early entry into the world of genomes, which he came to champion after he and his mother were diagnosed with lymphoma.

Inova has one of the few laboratories in the country researching patients’ genes for inherited risk factors. Every baby born at Inova has a gene profile created, he said.

“I became convinced that was the biggest scientific discovery since World War I when doctors discovered bacteria and viruses,” he said. Genomes are “the first time you could see the future of your health.”

Singleton enlisted Dr. John Neiderhuber, appointed by President George W. Bush in 2006 to be the director of the National Cancer Institute, to run Inova’s genomics program. They’ve partnered with the University of Virginia to bring a regional campus of the university’s medical school to Inova.

Neiderhuber said he’ll miss Singleton’s “folksy” approach and his genuine interest in understanding the science that drove his business decisions.

“He wanted to seriously take Inova to a whole other level,” Neiderhuber said. “He’s spent a whole lifetime building this system, and everyone owes him a lot for that.”

Singleton’s tenure has not been without controversy. In 1991 Singleton was criticized for taking a salary of $394,898, more than any other hospital executive in Virginia. And over the years, as Singleton grew Inova and took over smaller health-care entities, he’s been accused of operating the nonprofit system as a monopoly.

He’s also been recognized for his charitable work. He runs a community development organization for Haiti and advocated for more affordable housing in Northern Virginia so that lesser paid hospital staff wouldn’t be priced out of the area.

He’s optimistic about the future of health care, particularly doctors’ abilities to personalize medicine to focus on keeping patients well and avoid illness. Yet after more than three decades in the industry, he still worries about dramatic disparities in access to better care.

“There are a lot of people who can access some of the best health care in the world, they have access to really good care and professionals, but alongside that is a large and growing group of people who have real difficulty accessing health care,” he said. “The gaps between the haves and have nots are getting wider, not narrower.”