Spherocytosis is an inherited blood disease in which the erythrocytes (red blood cells) are spherical instead of biconcave.
Spherocytosis is an inherited blood disease in which the erythrocytes (red blood cells) are spherical instead of biconcave. This condition is inherited in a dominant fashion, with SPH (the mutant allele) dominant to SPH . In people with spherocytosis, the spleen “reads” the spherical red blood cells as defective and removes them from the bloodstream, leading to anemia. The spleen in different people removes the spherical erythrocytes with different efficiencies. Some people with spherical erythrocytes suffer severe anemia and some mild anemia, yet others have spleens that function so poorly there are no symptoms of anemia at all. When 2400 people with the genotype SPH SPH were examined, it was found that 2250 had anemia of varying severity, but 150 had no symptoms.a) Does this description of people with spherocytosis represent incomplete penetrance, variable expressivity, or both? Explain your answer.b) Can you derive any values from the numerical data to measure penetrance or expressivity?
