Bald

What is the expected frequency of pattern-bald males and pattern bald females in the population?

Pattern baldness in humans is an autosomal, sex-influenced trait; it is dominant in males and recessive in females. A male with at least one copy of the pattern baldness (PB) is bald; however, two copies of this allele must be present for a female to be bald. The frequency of the PB allele in a particular population has been estimated to be 0.3. Assuming random mating, what is the expected frequency of pattern-bald males and pattern bald females in the population?

Public Comments

1. To make simple, b is allele for baldness and B is for normal. p(B) = 0.7 q(b) = 0.3 According to Hardy-Weinberg: (p + q)^2 = p^2 + 2pq + q^2 So, the frequency of p^2(BB) = (0.7)^2 = 0.49 (normal males and females) 2pq(Bb) = 2 x 0.7 x 0.3 = 0.42 (bald males or normal females) q^2(bb) = (0.3)^2 = 0.09 (bald males and females) Since in males, b is dominant over B; and in females B is dominant over b, then the expected frequency of - pattern-bald males = 1/2 (sex) x (0.42 + 0.09) (baldness) = 0.255 - pattern-bald females = 1/2 (sex) x (0.09) (baldness) = 0.045 and - normal males = 1/2 x 0.49 = 0.245 - normal females = 1/2 x (0.49 + 0.42) = 0.455