Robert Nussbaum, a board certified internist and medical geneticist, specializes in the care of adults with hereditary disorders. (Marvin Joseph/The Washington Post)

“In terms of screening, we know that from the work we’ve done that only half of the people who end up with a positive genetic test indicating there’s a strong predisposition for cancer would have been tested under current, fairly narrow guidelines. I think the guidelines need to be broadened. That’s quite different from saying the entire population should be screened. But I do think that genetic testing is not being offered as widely as probably it should be.

“I think the major limitation right now is we don’t know how to interpret the vast majority of variation in the human genome. There are millions of differences between any two individuals, and even in the parts of the 2 percent of the genome that contains the coding, there are tens of thousands of differences. We don’t know how to interpret the vast majority of them. That’s a part of the current thrust to make the data available so that we can do research and really understand it.

“I’m very passionate about the point that we are not going to make great progress if we don’t free up all the data that’s being generated both in genetic testing companies and on the research side.”

Robert Nussbaum , chief medical officer, Invitae

This excerpt was from the December 6 Washington Post Live program Chasing Cancer. Video of the discussions can be see at Wapo.st/chasingcancer.