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OVERVIEW
This page is dedicated to organizing various examples of standardized exam questions whose answer is Lesch-Nyhan syndrome. While this may seem a odd practice, it is useful to see multiple examples of how Lesch-Nyhan syndrome will be characterized on standardized exams (namely the boards and the shelf exams). This page is not meant to be used as a traditional question bank (as all of the answers will be the same), however seeing the classic “test” characterization for a disease is quite valuable.
KEY CHARACTERISTICS OF THIS CONDITION (ON EXAMS)
When it comes to standardized exams, each condition has its own “code” marked by key buzzwords, lab findings, clues, etc. If you are well versed in this code you will be able to more quickly identify the condition that is being discussed, and get the right answer on the exam you are taking. Below is the “code” for Lesch-Nyhan syndrome.
- Intellectual disability
- Self mutilating behavior is very specific to this condition (such as chewing on the hands).
- Dystonia
- Hyperuricemia can be seen on serum studies
QUESTION EXAMPLES
Question # 1
Explanation # 1
Question # 2
Explanation # 2
TESTABLE FACTS ABOUT THIS CONDITION (BEYOND ITS IDENTIFICATION)
Many questions on standardized exams go beyond simply recognizing the underlying condition. Often there are specific testable facts regarding some aspect of the disease’s pathophysiology/management/clinical implications that are commonly asked. Some of these are listed below:
- Base cause: mutation in the HGPRT gene
- Mode of inheritance: X-linked recessive.
- Deficient enzyme: caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT)
- Consequence of deficiency: Defective purine salvage system. Cannot convert hypoxanthine to IMP and guanine to GMP. Produces more uric acid as a result.
- Complications: gout (due to hyperuricemia)
Page Updated: 04.17.2017