Postulated benefits of a mutated CFTR protein gene includes improved ability to survive after infection with various microbes; as mentioned above, there is evidence for CF carrier state benefit against cholera, typhoid, and tuberculosis.4 Survival benefits have presumably led to the current high prevalence of CFTR mutations present in the Caucasian population; approximately one out of every 20 to 25 Caucasian individuals is at least heterozygous for a CFTR protein gene mutation [8, 10, 32, 53]. Here, CFTR is linked to tuberculosis.