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B. Radiation induced
C. Chemotherapy induced
D. Mutation of Rb gene
Ans. C. (chemotherapy induced)
A patient has retinoblastoma. He is also likely to develop Mandibular osteosarcoma if the pathogenetic causes are the following EXCEPT
A. p53 gene mutationB. Radiation induced
C. Chemotherapy induced
D. Mutation of Rb gene
Ans. C. (chemotherapy induced)
Explanation
1. Patients with hereditary retinoblastomas have up to 1,000 times greater risk of subsequently developing osteosarcoma, attributed to germ-line mutations in the RB gene.
1. Patients with hereditary retinoblastomas have up to 1,000 times greater risk of subsequently developing osteosarcoma, attributed to germ-line mutations in the RB gene.
2.
Loss of heterozygosity, structural rearrangements, or point mutations in the RB
gene is also present in 60 70% of sporadic tumors.
3.
“Abnormalities in genes that regulate cell cycling, such as p53, CDK4, p16,
11JK4A, CYCLIN Dl, and MDM2 have also been implicated in the genesis of
nonhereditary osteosarcomas”— Robbin’s
4.
“The risk of osteosarcoma developing in facial bones increases greatly if
external beam irradiation has been used to treat the retinoblastoma” Kanski
5. Osteogenic sarcoma is the most common second
malignant neoplasm in survivours of familial or bilateral retinoblastomas. This
disease is caused by a genetic mutation in Rb give on chromosome 13, which only
increases the risk of de novo osteosarcoma
but also potentiates the osteosarcoma—inducing ability of ionizing radiation.
