CFTR and cystic fibrosis: Indeed, it has been proposed that the high carrier rate for CFTR mutations among Caucasians is due to an evolutionary selective advantage against infectious disease, with candidate agents including cholera (Gabriel et al., 1994), typhoid fever (Pier et al., 1998), and tuberculosis (Meindl, 1987), in which the pandemic in the early 1600s could explain the modern-day CF incidence rates in European-descendent populations (Poolman and Galvani, 2007).