MEDizzy - A 22-year-old woman gives birth at term to a boy after an

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The Eye Pathology

A 22-year-old woman gives birth at term to a boy after an uncomplicated pregnancy. No abnormalities are noted on a newborn physical examination. During infancy, a well-infant checkup shows leukocoria in the right eye. The eye is enucleated. Molecular analysis of the enucleated tumor indicates loss of cell cycle control in the tumor cells. In comparison, the infant’s skin fibroblasts do not show any molecular abnormality. Which of the following statements regarding this infant is most accurate?

ExplanationThis infant has a sporadic form of retinoblastoma. Both mutations probably arose in the retinoblasts. The infant did not inherit susceptibility to develop retinoblastoma because both copies of the RB gene are normal in unaffected somatic cells (fibroblasts). If he had inherited one copy of the mutant (or deleted) RB gene, all the cells in the body would have only one normal copy of the RB gene. His siblings are at no increased risk of developing retinoblastoma, and he is at no increased risk of developing osteosarcoma. For similar reasons, the risk of developing a retinoblastoma in the left eye also is no greater than that of the general population