Irish Setters can be blind as a result of the influence of a recessive gene. A pair of animals with a normal phenotype has 5

Irish Setters can be blind as a result of the influence of a recessive gene. A pair of animals with a normal phenotype has 5 puppies, two of whom were blind. Establish the genotypes of the parent couple and offspring.

Let the gene for normal vision of Irish setters be A, then the gene for blindness is a (since it is recessive). If a pair of parent animals has normal vision, then their genotypes contain a dominant gene A. The fact that blind puppies were born in their offspring, along with sighted ones, indicates that the parents were heterozygous – Aa. The recessive gene manifests itself only in a homozygous state, which means that both parents had it. Answer: by genotype, parents are Aa, sighted puppies are AA or Aa, blind puppies are aa.