Phenotypic Ratio from Genetic Cross

In a study on a specific gene involved in regulating skin pigmentation, researchers discovered two alleles: a dominant allele (A) that leads to dark pigmentation, and a recessive allele (a) that results in light pigmentation. A genetic cross was performed between two heterozygous individuals (Aa x Aa). The researchers also noted that the pigment-producing enzyme encoded by the A allele tends to undergo a mutation that can lead to reduced enzyme activity. This mutation can either be inherited or sporadic.

What is the expected phenotypic ratio of the offspring resulting from this genetic cross?