Chapter C, Problem 3P

C.3 For the retinal cancer retinoblastoma, the inheritance of one mutated copy of RBI from one of the parents is often referred to as a mutation that produces a $\text{“}$ dominant predisposition to cancer. $\text{”}$ This means that the first mutation does not produce cancer but makes it very likely that cancer will develop.

Define the “two $\text{-}$ hit hypothesis” for retinoblastoma.

Explain why cancer is almost certain to develop with the inheritance of one mutated copy of RBI.

Using ${\text{RBI}}^{\text{+}}$ for the normal wild $\text{-}$ type allele and ${\text{RBI}}^{\text{-}}$ for the mutant allele, identify the genotype of a cell in a retinoblastoma tumor.

What is the genotype of a normal cell in the retina in a person who has sporadic retinoblastoma? What is the normal cell genotype if the person has hereditary retinoblastoma? Explain the reason for the difference between the genotypes.