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  #1  
Old 06-28-2012
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Default After an uncomplicated pregnancy, a 20-year-old woman gives birth

After an uncomplicated pregnancy, a 20-year-old woman gives birth at term to a boy. No abnormalities are noted on a newborn physical examination. During infancy, a well-infant checkup shows leukokoria in the right eye. The eye is enucleated. Molecular analysis of the enucleated tumor cells indicates loss of both normal alleles of the RB gene. In comparison, the infant's skin fibroblasts do not show any abnormality at the RB locus. Which of the following regarding the intraocular tumor in this infant is most accurate?
(A) Future development of osteosarcoma
(B) Inheritance of a mutated RB gene locus
(C) Loss of both RB gene copies in the tumor
(D) Risk for a contralateral eye neoplasm
(E) Siblings at risk for a similar tumor
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Old 06-28-2012
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Default my answer

I'll go with (C) Loss of both RB gene copies in the tumor

most of the cases of retinoblastoma are sporadic. deletion of both Rb copies leads to uncontrolled transition of cells from G1 to S phase.

in familial type (B,D and E) mutant RB gene is inherited through the germ cells line & there is increased risk of bilateral retinoblastoma.

I would say osteosarcoma is a distractor
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Old 06-28-2012
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C) Loss of both RB gene copies in the tumor - sporadic RB.
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Old 06-29-2012
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D...Risk to loose another eye?
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Old 06-29-2012
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Default its C..

This scenario represents sporadic retinoblastoma.....rest option are features of familial retinoblastomas

@casandra------familial retinoblastoma is associated with higher risk of osteosarcoma in adolescent life...it isn't a distractor.......
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