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Erythrocyte abnormalities in a hypoalphalipoproteinemia syndrome resembling fish eye disease
D V Godin1, M E Garnett, G Hoag
1Department of Pharmacology, University of British Columbia, Vancouver, Canada.
Abstract:
Erythrocyte membrane (EM) abnormalities in a 16-yr-old boy with hypoalphalipoproteinemia resembling fish eye disease (FED-LS) were investigated. The proband's erythrocytes had markedly decreased osmotic fragility with target cells observed in the peripheral film. Analysis of his EM lipids revealed normal cholesterol and phospholipid content but a marked increase in phosphatidylcholine with concomitant decreases in phosphatidylethanolamine and sphingomyelin. Of the EM enzymes examined, acetylcholinesterase and superoxide dismutase activities were decreased while those of Na+-K+ ATPase, catalase and glutathione reductase were normal. 51Cr erythrocyte survival in the patient was slightly decreased. The observed changes in a number of structural and functional properties of erythrocytes in this disorder are indistinguishable from those previously described in homozygotes for familial lecithin:cholesterol acyltransferase (LCAT) deficiency. Thus, it is possible that in both of these disorders an abnormality of plasma LCAT activity causes, either directly or indirectly, functional and structural changes in the erythrocyte membrane.
Insights
Erythrocyte membrane abnormalities were found in a patient with hypoalphalipoproteinemia similar to fish eye disease. These changes suggest a potential link to lecithin:cholesterol acyltransferase deficiency.
Area of Science:
- Biochemistry
- Hematology
- Lipid Metabolism
Background:
- Hypoalphalipoproteinemia can present with unique clinical features, sometimes resembling rare genetic disorders.
- Fish eye disease (FED) is characterized by corneal opacities and low high-density lipoprotein (HDL) levels.
- Erythrocyte membrane (EM) structure and function are crucial for red blood cell integrity and oxygen transport.
Purpose of the Study:
- To investigate erythrocyte membrane abnormalities in a patient with hypoalphalipoproteinemia presenting with features similar to fish eye disease (FED-LS).
- To compare the observed EM changes with those found in familial lecithin:cholesterol acyltransferase (LCAT) deficiency.
Main Methods:
- Analysis of erythrocyte osmotic fragility and peripheral blood film.
- Lipid composition analysis of the erythrocyte membrane.
- Assay of key erythrocyte membrane enzyme activities.
- Erythrocyte survival studies using 51Cr labeling.
Main Results:
- The patient's erythrocytes exhibited decreased osmotic fragility and target cells.
- EM lipid analysis revealed normal cholesterol and phospholipids but altered phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin levels.
- Decreased activities of acetylcholinesterase and superoxide dismutase were noted, while Na+-K+ ATPase, catalase, and glutathione reductase remained normal.
- Slightly decreased erythrocyte survival was observed.
Conclusions:
- The erythrocyte membrane alterations in this FED-LS patient are indistinguishable from those in familial LCAT deficiency homozygotes.
- A plasma LCAT activity abnormality may be the underlying cause of both structural and functional EM changes in these conditions.