RetinoblastomaRetinoblastoma

by Michele Chasteenby Michele Chasteen

What is Retinoblastoma?What is Retinoblastoma?

Tumor of the eye that can occur at a high frequency in children and sporadically at an older age.

Occurs in hereditary and non-hereditary forms (sporadic).

Caused by a deletion on chromosome 13 with a locus of 13q14.

The RB geneThe RB gene

Gene that causes retinoblastoma.Gene that causes retinoblastoma.

Tumor suppressor gene.Tumor suppressor gene.

Loss of normal function of RB gene leads to Loss of normal function of RB gene leads to malignancy. malignancy.

Order: Mutation - deregulated cell cycle - Order: Mutation - deregulated cell cycle - uncontrolled cell division - tumor development.uncontrolled cell division - tumor development.

HereditaryHereditary RetinoblastomaRetinoblastoma

Inherited as a dominant genetic trait.

Members of high-risk families inherit one normal allele and one abnormal allele.

Children that inherit an abnormal allele inherit a strong disposition for developing the disease.

After retinal cell undergoes one spontaneous mutation, it is left with two mutated alleles.

Cell divides uncontrollably giving rise to retinal tumor.

Develops at a young age and affects both eyes.

Sporadic RetinoblastomaSporadic Retinoblastoma Very rare.Very rare.

Requires that two separate spontaneous mutations Requires that two separate spontaneous mutations must occur in the RB gene.must occur in the RB gene.

Retinoblastoma occurs only after both alleles carry the Retinoblastoma occurs only after both alleles carry the mutation.mutation.

Cell divides uncontrollably giving rise to retinal tumor.Cell divides uncontrollably giving rise to retinal tumor.

Develops at an older age and affects only one eye.Develops at an older age and affects only one eye.

SummarySummary

Hereditary or sporadic.

Hereditary form requires only one spontaneous mutation.

Sporadic form requires two separate spontaneous mutations.

Retinoblastoma is caused by a mutation in RB gene (tumor suppressor gene)

Questions??Questions??