Jonathon T. answered • 11/21/22
Experienced Cell Biology Instructor and Practicing PA-C
If you want to think of this in terms of metabolism, consider the incomplete dominance observed in Tay Sachs disease. As you are likely aware, incomplete dominance is when no allele takes dominance meaning there is some form of intermediate expression. We classically think of an intermediate color between that observed for homozygous recessive phenotypes and homozygous dominant phenotypes. Tay Sachs is a metabolic, genetic disorder in which the there is a deficiency in a gene product beta-hexoaminidase on chromosome 15. You have two chromosome 15s in each cell, one from mom and one from dad. When one produces a nonfunctional gene product, there is still some level of wild type protein expression from the unaffected chromosome. Heterozygous individuals will moderately reduced functional protein product levels. Since this enzyme is important for lipid metabolism, the moderately reduced levels do not result in no breakdown, but the level is not sufficient to avoid producing a phenotype we may recognize as a genetic syndrome primarily due to lipid accumulation in the brain.
Hopefully this hits on what you were looking for.
