Conditions · Metabolism: cholesterol and lipoproteins
Abetalipoproteinemia (Bassen–Kornzweig syndrome) !
A rare inherited disorder in which ApoB lipoproteins cannot form; fat and fat-soluble vitamins are poorly absorbed.
Updated 2026-11-01
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What it is
An autosomal recessive disorder caused by lack of microsomal triglyceride transfer protein (MTP), which prevents chylomicron and VLDL formation.
Who gets it
Rare: just over 100 cases have been described worldwide. It is suspected in infants with fat malabsorption and very low cholesterol.
Causes
- Two MTTP gene variants
- Autosomal recessive inheritance
Risk factors
- Carrier parents
- Related parents
Pathophysiology
Without MTP, ApoB gets no lipid and is degraded: no chylomicrons leave the gut and no VLDL leaves the liver. Fat is trapped in enterocytes (steatorrhoea) and the liver fills with fat. Blood lacks LDL, triglycerides and fat-soluble vitamins; vitamin E deficiency damages retina and spinal cord, and red cells become spiky (acanthocytes).
Symptoms and signs
- Fatty diarrhoea (steatorrhoea) and bloating from infancy
- Failure to thrive
- Ataxia, loss of reflexes and of deep sensation
- Progressive vision loss (pigmentary retinopathy)
- Fatty liver
Diagnosis
- Clinical
- Fat malabsorption in an infant with very low cholesterol and triglycerides; later, ataxia and retinopathy.
- Tests
- Very low total cholesterol, nearly undetectable triglycerides, absent ApoB, acanthocytes on the smear, vitamin A, E and K levels, prothrombin time and MTTP genetic testing; duodenal biopsy shows fat-laden enterocytes.
- Imaging
- Abdominal ultrasound for fatty liver; fundus examination and optical coherence tomography of the retina.
Treatment
- Lifestyle
- Diet low in long-chain fat, with medium-chain triglycerides under supervision
- Medical
- Supplements of vitamin E, the most important, and of vitamins A, D and K
- Follow-up
- Neurological, eye and liver follow-up
Complications
- Blindness from retinopathy
- Progressive neuropathy and ataxia
- Hepatic steatosis and fibrosis
- Coagulopathy from vitamin K deficiency
Prognosis
Starting vitamin E early can prevent or slow nerve and retinal damage.
Test yourself
Think of the answer, then tap the question to see it.
Which protein is missing in abetalipoproteinaemia?
MTP (microsomal triglyceride transfer protein), which loads lipid onto ApoB.
What shape are the red cells in this disease?
Acanthocytes: spiky cells caused by altered membranes.
Which vitamin is key to preventing nerve damage?
Vitamin E, which cannot reach the tissues without lipoproteins.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Abetalipoproteinemia: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026); Bassen-Kornzweig syndrome: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); MTTP gene: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.
