BIOL 202 Lecture Notes - Lecture 30: S Phase, Secondary Mutation, E2F
Document Summary
Rare childhood cancer of the eye: sometimes causes leukocoria (white reflex in the pupil, 40% familial, can be unilateral or bilateral. Difference in kinetics of unilateral and bilateral retinoblastoma shows that unilateral blastoma tumor development occurs earlier on in childhood: unilateral cases tend to be sporadic, while bilateral cases tend to be familial. Two separate genetic defects (mutations) cause retinoblastoma: two hits must happen to a single cell. Rarer event takes longer to develop. Inherited cases: patients are born with the first hit, therefore chances of developing two hits is high. Only one more hit has to occur sporadically: shows mutations of a single gene in both alleles. 2 mutations in rb1 (tumor suppressor gene) Therefore, oncogenes act in a dominant manner while rumor-suppressor gene act in a recessive manner. Nf1 (gtpase activator: located in cytoplasm, mutation in both alleles of nf1 has similar consequences to mutations in one allele for ras protein-coding genes.
