Question

In mouse agouti locus is hypostatic to pigment development locus. If C is for pigment development, and A is for agouti, and recessive alleles in agouti locus gives black colour and recessive in pigment locus gives white colour, what will be the phenotype of A/- c/c and a/a c/c.

(a) Agouti, white

(b) Black, agouti

(c) Black, black

(d) White, white

I got this question at a job interview.

My question is from Epistasis in division Extension and Deviation from Mendelian Genetic Principles of Cytogenetics

Answer 1

Correct answer is (d) White, white

Explanation: In this case the C gene is epistatic, so unless colour is developed due to C/- there will be no expression of A locus. In both of these cases, C locus has c/c/ alleles, so both the mice are white.