Page Contents
OVERVIEW
This page is dedicated to organizing various examples of standardized exam questions whose answer is abetalipoproteinemia. While this may seem a odd practice, it is useful to see multiple examples of how abetalipoproteinemia 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 abetalipoproteinemia.
- Severe fat malabsorption: this results in steatorrhea, failure to thrive
- Spinocerebellar degeneration: this will be due to vitamin E deficiency after a while. Can notice gait ataxia and other neurological manifestations.
- Retinitis pigmentosa: this is a later manifestation. Black pigmentation of the retina (and its deterioration)
- Acanthocytosis visible on blood smear: red blood cells with spiky projections
- Low cholesterol will be noted on serum studies (if performed).
QUESTION EXAMPLES
Question # 1
A 17 year old woman with a slight intellectual disability is brought to the clinic because she has been experiencing difficulty seeing clearly in reduced light for the past few days. Her past medical history is notable for a lifelong history of chronic diarrhea that is smelly and difficult to flush. A year ago she also devolved a lack of muscle control in all of her limbs, and developed generalized weakness. A funduscopic exam reveals the presence of bilateral retinitis pigmentosa. A neurological exam reveals gait ataxia, and the loss of deep tendon reflexes. Serum studies reveal a total cholesterol concentration of 48 mg/dL, and a blood smear is remarkable for erythrocytes that possess spiny projections. What is the likely diagnosis in this patient?
Explanation # 1
Chronic diarrhea (steatorrhea) + spinocerebellar degeneration (weakness, lack of muscle control, loss of DTRs, gait ataxia) + retinitis pigmentosa + low serum cholesterol + acanthocytosis = abetalipoproteinemia
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:
- Cause: deficiency in ApoB48 and Apo B100
- Consequence of deficiency: Chylomicrons, VLDL, LDL
- Inheritance pattern: autosomal recessive
- Treatment: restriction of long-chain fatty acids. Large oral doses of vitamin E.
Page Updated: 04.15.2017