WBR0782
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| Author | [[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathophysiology |
| Sub Category | SubCategory::Head and Neck, SubCategory::Oncology |
| Prompt | [[Prompt::A 1-week-old boy is brought to the pediatric clinic for a well-baby checkup. The mother reports that her child has been doing well since he has been home. He was born full-term via normal vaginal delivery without any perinatal complications. His first physical exam was unremarkable according to the hospital charts. He has been exclusively breast fed and tolerating several feeds a day. On physical exam, all seems within normal limits, but the pediatrician notices something unusual on eye exam (shown below). Which of the following mutations can explain the findings in this child?
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| Answer A | AnswerA::Elastin gene mutation |
| Answer A Explanation | AnswerAExp::Elastin mutations are involved in the pathogenesis of Marfan's syndrome. |
| Answer B | AnswerB::Retinoblastoma gene mutation |
| Answer B Explanation | AnswerBExp::Retinoblastoma gene mutations are responsible for development of retinoblastoma which can cause leukocoria. |
| Answer C | AnswerC::FGFR3 gene mutation |
| Answer C Explanation | AnswerCExp::FGFR3 gene mutations are responsible for achodroplasia. |
| Answer D | AnswerD::Collagen gene mutation |
| Answer D Explanation | AnswerDExp::Collagen gene mutations are seen in patients with osteogenesis imperfecta. |
| Answer E | AnswerE::p53 gene mutation |
| Answer E Explanation | AnswerEExp::p53 gene mutations are responsible for the development of several cancers including osteosarcoma, breast and colon cancer. |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::Leukocoria refers to an abnormal white reflection from the retina where a usual red reflex is expected. Leukocoria in infants raises concern for two important entities: congenital cataracts and retinoblastoma. Retinoblastoma is a rapidly progressing tumor that develops from cells of a retina. It can either be sporadic or inherited. In both cases, the tumor develops due to a mutation in the RB1 gene whose protein product, the retinoblastoma protein, is a tumor suppressor that inhibits G1-to-S transition and regulates the cell cycle. In its inherited form, the mutation of the RB1 gene predisposes to other malignancies later in life. Educational Objective: Leukocoria is an abnormal white reflex that can be seen in children with retinoblastoma. Retinoblastoma occurs due to a mutation in the RB1 gene. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Retinoblastoma, WBRKeyword::Leukocoria, WBRKeyword::White reflex, WBRKeyword::Rb |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
