Apple's health boss, Anil Sethi, has left the company to start venture focusing on helping very sick patients after his sister died from cancer.

Sethi's medical record start-up Gliimpse was acquired by Apple in August 2016, with Sethi named director of the health team. Sethi also worked at Apple as an engineer in the late 1980s but doesn't credit that as a factor in the acquisition. Instead, he suspects, it was his team's expertise at aggregating medical information, while adhering to federal privacy requirements.

"At one point, Cupertino looked at 50 companies or so but they picked our team," he said. "I can't speak for them but one of the things we did is showed them a demo of what the technology could do without a slide deck."

Apple has been looking at ways to turn the iPhone into the central vault for people's medical information. That's Sethi's expertise, which he views as a key way to get around health care's "interoperability problem."

Interoperability, meaning the ability to share medical information securely between hospitals and clinics, is still a challenge in health care. It particularly affects those with serious health conditions with records scattered among dozens of doctors.