The human blood types M and N are determined by codominant a

The human blood types M and N are determined by codominant alleles, so that the MN phenotype is distinguishable from both M (genotype MM) and N (genotype NN) homozygote9. A particular population has the following percentages of these blood groups: 15% M, 61% MN, and 24% N. Is this population in Hardy-Weinberg equilibrium? If not, how does it differ, and what are possible reasons for the difference?

Solution

The Hardy–Weinberg law, states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.

ie for p and q; p + q = 1

the binomial expansion of (p + q)² = p² + 2pq + q² = 1  as the genotype frequencies must sum to one.

ie gives the same relationships.

in this case M=0.15

MN=0.61

N=0.24

(M+N)² = M²+2MN+N² = 0.15² + 2x0.61 + 0.24²

   ^=1.3001

^As (M+N)² is not =1, this does not follow  Hardy–Weinberg law