Serum lipoproteins in plasma lecithin:cholesterol acyltransferase deficiency, studied by electron microscopy

Serum lipoproteins from a patient with LCAT deficiency have been studied by electron microscopy and compared with lipoproteins from a normal individual and a patient with hyperlipo‐proteinemia of type IV. Particles of density < 1.006 g/ml from the LCAT deficiency patient were within a range of 230–3000 Å in diameter, whereas the diameters of the corresponding particles from the other two subjects fell within a range from 230 to 900 Å. A mean diameter of approximately 200 Å was found for the low density lipoproteins (l.019–1.063 g/ml) from the three subjects investigated. In LCAT deficiency the high density lipoprotein (1.063–1.195 g/ml) particles demonstrated a tendency to rouleau‐formation, giving the molecules a coinlike appearance with a mean diameter of 162 Å, and a mean thickness of 46 Å. In electron micrographs of HDL particles from the other two subjects studied, rouleau‐formation was not observed, and the mean diameters were of 82 and 85 Å, respectively. By gel filtration on Sephadex G‐200 of the HDL fraction from the patient with LCAT deficiency two populations of particles were found, one with a mean particle diameter of 163 Å and one with particle diameters of 35–56 Å.