2. Retinoblastoma by Michele Chasteen

3. What is Retinoblastoma? n n Tumor of the eye that can occur at a high frequency in children and sporadically at an older age. n n Occurs in hereditary and non-hereditary forms (sporadic). n n Caused by a deletion on chromosome 13 with a locus of 13q14.

4. The RB gene n Gene that causes retinoblastoma. n Tumor suppressor gene. n Loss of normal function of RB gene leads to malignancy. n Order: Mutation - deregulated cell cycle - uncontrolled cell division - tumor development.

5. Hereditary Hereditary Retinoblastoma n n Inherited as a dominant genetic trait. n n Members of high-risk families inherit one normal allele and one abnormal allele. n n Children that inherit an abnormal allele inherit a strong disposition for developing the disease. n n After retinal cell undergoes one spontaneous mutation, it is left with two mutated alleles. n n Cell divides uncontrollably giving rise to retinal tumor. n n Develops at a young age and affects both eyes.

6. Sporadic Retinoblastoma n Very rare. n Requires that two separate spontaneous mutations must occur in the RB gene. n Retinoblastoma occurs only after both alleles carry the mutation. n Cell divides uncontrollably giving rise to retinal tumor. n Develops at an older age and affects only one eye.

7. Summary n n Hereditary or sporadic. n n Hereditary form requires only one spontaneous mutation. n n Sporadic form requires two separate spontaneous mutations. n n Retinoblastoma is caused by a mutation in RB gene (tumor suppressor gene)

8. Questions??