Human Autosomal Recessive Conditions

∞ generated and posted on 2016.08.28 ∞

Blue eyes, lack of widow's peak, attached earlobes, type O blood, rh- blood type, cystic fibrosis, Tay-Sachs disease, sickle-cell disease.

For individuals to display autosomally recessive conditions they must possess two copies of the recessive allele whereas the dominant condition requires only one copy of the dominant allele (the other allele, that is, can be recessive).

Pedigree Analysis

Figure legend: So, just what is my eye color genotype? With grandfather's eyes, paternal aunt's eyes, and daughter's eyes all blue, it seem fairly certain that my grandmother, father, and myself all carry or carried a blue allele as well. My father and I presumably share the same blue allele that my daughter now carries as half her complement, while my father's brown came from his mother (and thus her blue is found in my aunt but not my father nor myself). The fact that a maternal aunt has blue eyes, however, complicates this story. My mother, brother, son, and myself, on the other hand, share green hazel eyes, all presumably traceable to my mother, or is it just the tendency to "hazel out" that can be traced to her? Note that circles are female, squares are males, horizontal lines between symbols indicate successful matings (which in this case I'm assuming are synonymous with marriages), and vertical lines (along with horizontal branchings) connect direct ancestors to direct descendants.

My daughter's eyes are blue potentially because of the blueness of both my wife's and paternal grandfather's eyes. My paternal grandmother had brown eyes as too does my father. Since his father had blue eyes then my father must be a brown-blue heterozygote, expressing the dominant brown which he received from my grandmother. My eyes are not blue but instead a green hazel, as too are my son's eyes. My assumption, therefore, is that my son received one of my eye color alleles and my daughter the other, whereas my wife supplied blue to both.