Pathophysiology
type of lipid disorder
Signs and Symptoms
1) sensory ataxia 2) loss of deep tendon reflexes 3) retinitis pigmentosa
Characteristic Test Findings
Laboratory – 1) absence of chylomicrons, LDLs, and VLDLs 2) decreased triglycerides 3) decreased cholesterol 4) only mild anemia despite significant acanthocytosis (Burr’s cells)
Histology/Gross Pathology
1) demyelinization of selective CNS tissues, particularly posterior columns 2) acanthocytosis (RBCs look like they have spurs protruding from membranes) 3) pigmentary retinopathy 4) epithelial cells of gut have lipid vacuoles
Biochemistry
absorptive cells in GI tract lack ability to make apoprotein B, which is used to build the membranes of chylomicrons and lipoproteins
Inheritance/Epidemiology
autosomal recessive
Treatment
1) avoidance in diet of long-chain triglycerides that require chylomicrons (apoprotein coat) for transport 2) substitution of medium-chain triglycerides that do not require chylomicrons for transport across the epithelial membrane in the gut
Tips for USMLE
main hallmarks – acanthocytosis (Burr’s cells), absence of apoprotein B, chylomicrons, LDLs, and VLDLs
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