Uncovering Rare Genetic Factors with Multiplex Germline Testing

At the American Society of Clinical Oncology (ASCO) 2018 annual meeting in Chicago, Illinois, Pauline Funchain MD, associate staff member in the Taussig Cancer Institute at the Cleveland Clinic, discussed the use of multiplex germline testing for rare diseases and cancers and explained the benefits of uncovering genetic factors.

Interview Transcript (modified slightly for readability):

Funchain: “We used to test 1 gene at a time. We would say, ‘Look, your family has breast and ovarian cancer, we’ll test you for BRCA.’ If that didn’t turn up positive, we would test for something else.

Now, we have next generation sequencing, and we can test any genes at once. The question is: how many genes and what genes [to] test because you’re not going to send every gene that you know of [for testing]. That’s part of what this research is trying to figure out. What are the high-yield genes for melanoma, and what is the genetic predisposition to melanoma?

I think what we’re finding is that we used to think that there were only certain cancers that were related to cancers that ran in families—such as breast cancer, ovarian cancer, colon cancer, Lynch syndrome, and other GI cancers—but [those with] melanoma weren’t really [considered]. Then you extend this [idea] to [the question of]: Are there other cancers that might also have a genetic predisposition that we haven’t thought of?

The next thing that comes to mind is lung cancer, not a rare disease, but we thought that was [caused by] smoking, and there was just an ASCO abstract that said 8% of unselected lung cancers have germline predispositions. This all comes back to rare diseases, because we have so few of them, sometimes you can’t draw the line between a rare disease and a genetic predisposition.

If you look at our cohort, we had a couple of mucosal melanomas and uveal melanomas, which are very rare diseases, and it looks like there’s a predisposition. I think if we look further into these rare diseases, we’re also going to find things we didn’t know [of] in terms of connections.”