If an autosomal recessive disorder which shows Hardy-Weinberg equilibrium has an incidence of 1 in 6400 then the frequency of carriers is approximately _______.

A. 1 in 20

B. 1 in 40

C. 1 in 80

D. 1 in 160

The carrier frequency equals approximately double the square root of the disease incidence i.e. 2 X 1/80 = 1/40