Question

Consider the following allele frequencies for three SNPs

	SNP1	SNP2	SNP3
Africa	A:20%,T:80%	G:70%,T:30%	C:20%,A:80%
Asia	A:50%,T:50%	G:20%,T:80%	C:20%,A:80%
South America	A:60%,T:40%	G:80%,T:20%	C:70%,A:30%

For each genotype, calculate the genotype frequency in Africa and Asia.

Can someone please help me? Showing all the steps. I don't know what to do. Thank you!

Answer 1

genotype frequency is the no. of individual with a perticular genotype divided by total individuals in a population.

For africa, SNP1: there are two genotype A & T, and there percentage is given

so frequencey of A = 20/100 =0.2 & frequency of T in the same way will be 0.8.

AFRICA SNP2: G = 70/100 = 0.7 & T = 30/100 = 0.3

ASIA SNP1: A=0.5, T=0.5, ASIA SNP2: G = 0.2, T = 0.8 & SNP3: C=0.2 & A = 0.8

If you want to consider all SNP together then in Africa

frequency of A = total individual with A genotype / total genotype

in this case total individual will be 300 (3 different SNPs given and each were given in percentage so count 100 for each as total individuals.)so (20+80)/300 = 0.33

frequency of T = (80+30)/300 = 0.36

frequency of G = 70/300 = 0.23

frequency of C = 20/300 = 0.06

For Asia in the similar way. A=0.43, T=0.43,G=0.06 & C=0.06