Phenotype

A phenotype is the physical/observable expression of a gene. In the context of color vision, the Phenotype is the “symptom”, i.e. the measurable defect, such as a Tritan defect. Each phenotype can generally be linked to several genotypes.

For red-green Colorblindness, the genotype and phenotype are closely linked, as there are few environmental factors that can have a significant effect.