WBR0390
| Author | [[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Genetics |
| Sub Category | SubCategory::Endocrine |
| Prompt | [[Prompt::A 32-year-old male patient presents to your office to inquire about a disease, which is prevalent in his family. He does not recall the name of the disease. Instead, he provides you with a pedigree, which an old physician created, illustrating a the affected and unaffected family members. The patient’s pedigree is displayed below. Which of the following diseases most likely prevails in this patient’s family?
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| Answer A | AnswerA::Leber’s hereditary optic neuropathy |
| Answer A Explanation | [[AnswerAExp::Leber’s hereditary optic neuropathy is a mitochondrial disease. All mitochondrial diseases are characterized by maternal transmission to offspring.]] |
| Answer B | AnswerB::Albinism |
| Answer B Explanation | [[AnswerBExp::Albinism has an autosomal recessive mode of inheritance.]] |
| Answer C | AnswerC::Hypophosphatemic rickets |
| Answer C Explanation | [[AnswerCExp::Hypophosphatemic rickets have an X-linked dominant mode of inheritance.]] |
| Answer D | AnswerD::Ocular albinism |
| Answer D Explanation | AnswerDExp::Ocular albinism has an X-linked recessive mode of inheritance. |
| Answer E | AnswerE::Schizophrenia |
| Answer E Explanation | AnswerEExp::X-linked, X-linked dominant, pedigree, genetics, inheritance, Hypophosphatemic rickets, transmission, inheritance pattern |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::The pedigree in this scenario demonstrates an X-linked dominant pattern of inheritance. In almost every scenario, daughters of affected fathers acquire the disease and sons of affected mothers are aquire the disease. Among the list of options, hypophosphatemic rickets, or vitamin D-resistant rickets, is the only disease with X-linked dominant inheritance. Hypophosphatemic rickets are characterized by the increased waste of phosphate at the renal proximal tubule level.
EducationalObjectives= An X-linked dominant inheritance pattern is characterized by transmission from affected fathers to daughters and affected mothers to sons. Hypophosphatemic rickets are an example of an X-linked dominant inheritance pattern, which causes phosphate wasting at the level of renal proximal tubules. |
| Approved | Approved::Yes |
| Keyword | |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
