Human Heredity 11th Edition by Michael Cummings

تمرين 12

The cystic fibrosis gene encodes a chloride channel protein necessary for normal cellular functions. Let us assume that if at least 5% normal channels are present, the affected individual has mild symptoms of cystic fibrosis. Having less than 5% normal channels produces severe symptoms. At least 50% of the channels must be expressed for the individual to be phenotypically normal. This gene has various mutant recessive alleles: Predict the percent of functional channels and severity of symptoms for the following genotypes:
A) heterozygous for CF100
B) homozygous for CF100
C) heterozygous, with one copy of CF100 and one of CF3
D) heterozygous, with one copy of CF1 and one copy of CF3