The incidence of cystic fibrosis, a recessive genetic disorder in the Caucasian population of United States, is

in every 2,500 individuals. Find the number of heterozygous carriers. (p + q = 1, p2 + 2pq + q2 = 1) A. 0.0392 B. 0.0254 C. 0.045

Cystic fibrosis occurs 1 in every 2,500 individuals.

Using Hardy Weinberg principle,

freq. of recessive allele / q2 = 1/2500 = 0.0004

Take the square root,

q = 0.02

freq. of dominant allele / p = q - 1

p = 0.98

freq. of heterozygous individuals = 2pq = 0.04

Therefore, the answer is 0.04, which is C.