SOCR 330 Lecture Notes - Pleiotropy, Cream Gene, Penetrance
Document Summary
Cr me gene in horses has 2 alleles: c and ccr. Trait is not expressed at all in some individuals while others with the same genotype do express trait. Rb gene in normal unmutated state helps regulate cell cycle. Children born with one mutated rb version of gene have 90% chance of developing retinoblastoma by age 5. 10% of rb individuals do not develop retinoblastoma. Trait is expressed in different amounts or intensities in different individuals with the same genotype. A variably expressive allele is always expressed (compare with variable penetrance) The polydactyly allele p is a dominant mutation causing the growth of extra digits (fingers and toes) Pleiotropy multiple phenotypic effects from one allele. Offspring from mating two manx cats (mm x mm) will segregate: 2 manx (mm) : 1 normal (mm) Autosomal genes express differently in male and female.
