My career in medicine beganwith a simple fascination: Why do certain diseases refuse to stay in one lane? Early in medical school, I found myself drawn to problems that involved multiple body systems at once—ones that demanded you zoom out and consider the entire body. For example, a clinical picture of unexplained swelling, a thickened and deteriorating heart, and progressive neuropathy would pique my curiosity and force me to slow down, considering possibilities beyond the usual suspects....