Which of the following is an inherited disorder characterised by significantly reduced levels of high-density lipoprotein (HDL) in the blood?

1. A

   Tangier disease

2. B

   Acrocallosal syndrome

3. C

   Adams-Oliver syndrome

4. D

   Adie syndrome

Appeared in: DSSSB 6 September 2024

Explanation

• Tangier disease is a rare genetic disorder defined by extremely low levels of HDL cholesterol, often below 5 mg/dL.
• It is caused by mutations in the ABCA1 gene, which is essential for the process of reverse cholesterol transport (moving cholesterol from tissues back to the liver).
• The defect leads to the accumulation of cholesterol esters in various tissues, particularly the reticuloendothelial system.
• A pathognomonic (classic) sign of Tangier disease is enlarged, orange-yellow tonsils, which is a direct result of this cholesterol buildup.

Why Other Options Were Wrong

• Option B: Acrocallosal syndrome is a neurodevelopmental disorder characterized by agenesis of the corpus callosum and polydactyly. It does not affect lipid metabolism.
• Option C: Adams-Oliver syndrome is a congenital disorder causing defects of the scalp, skull, and limbs. It is unrelated to lipoprotein levels.
• Option D: Adie syndrome is a neurological disorder affecting the autonomic nervous system, specifically the pupil of the eye and deep tendon reflexes. It has no link to cholesterol metabolism.

Related Visual

Clinical Relevance

• Nursing practice connection: Knowing Inherited disorders of lipid metabolism, specifically those affecting High-Density Lipoprotein (HDL) helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
• Nurses should recognize that while low HDL is a common cardiovascular risk factor, extremely low levels (less than 5-10 mg/dL) should prompt consideration of a rare genetic disorder like Tangier disease.
• The classic sign of orange tonsils is a key diagnostic clue. A nurse performing an oral assessment who notes this finding should ensure the patient is evaluated for a lipid disorder.
• Patients with Tangier disease are at an increased risk for premature atherosclerotic cardiovascular disease and peripheral neuropathy, requiring long-term monitoring and management.

How to Approach the Question

• First, analyze the question stem to identify the core concept. The key phrases are 'inherited disorder' and 'significantly reduced levels of high-density lipoprotein (HDL)'.
• This is a factual recall question that requires knowledge of specific genetic syndromes.
• Evaluate each option against the core concept.
• Recall or deduce the primary characteristic of Tangier disease. It is classically known for its profound impact on HDL levels.
• Consider the other options. Acrocallosal, Adams-Oliver, and Adie syndromes are associated with neurological, structural, or developmental abnormalities, not primary lipid metabolism defects.
• Select the option that directly matches the pathophysiological description in the stem, which is Tangier disease.

Concept Tested & Keywords

• Concept Tested: Inherited disorders of lipid metabolism, specifically those affecting High-Density Lipoprotein (HDL).
• Stem keywords: inherited disorder, reduced levels, high-density lipoprotein (HDL)
• Lead-in keywords: Which of the following
• Negative lead-in flag: false

Question ID

QoWqJV7VDAAk7a-6q_Bkuj

Copy ID

Reference Book

E6 Medicine Harrison 22e Part 2 pp. 1152-1154, 1145-1147

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 924-926