 In 1952, Paul di Sant'Agnese discovered abnormalities in sweat electrolytes; a sweat test was developed and improved over the next decade.The first linkage between CF and another marker (Paroxonase) was found in 1985 by Hans Eiberg, indicating that only one locus exists for CF.In 1988, the first mutation for CF, ΔF508 was discovered by Francis Collins, Lap-Chee Tsui, and John R. Riordan on the seventh chromosome.