Two cancers in a young family: It was either horribly bad luck or the tip-off to a deeper connection. The story unfolded when MSK’s Michael Walsh, a young pediatric oncologist, was caring for a boy undergoing a bone marrow transplant at St. Jude Children’s Research Hospital in Memphis, Tennessee. The child wasn’t responding as expected to standard therapies, suggesting something curious about the rare form of leukemia from which he suffered. Suspicious, Walsh inquired about the family’s health history—and was startled to learn that the boy’s father had died of brain cancer a couple years earlier, at age 31.