A pedigree is shown below for a disease that is autosomal dominant. What would be the genetic make up of the first generation ?

Options

A. AA,Aa
B. Aa,aa
C. Aa,AA
D. Aa,Aa

Answer

B

Explanation

As the disease is autosomal dominant hence, the male parent who is normalm must have the homozygous recessive genotype i.e., aa. The affected female can have either Aa or AA genotype. If the genotype is AA, all the progenies will surely be diseased but if the genotype is Aa there is 50 % chance of having normal offsprings. But unfortunately the couple has produced only affected progeny and each of them must have the genotype Aa.