Hypobetalipoproteinemia with abnormal prebetalipoprotein

Abstract A 47-year-old man who had cerebellar ataxia and low plasma lipid and lipoprotein levels is reported. His tendon reflexes were hyperactive and the plantar responses were extensor. There was no acanthocytosis. Total lipids (380 mg/dl), total cholesterol (106 mg/dl), esterified cholesterol (74 mg/dl), triglyceride (58 mg/dl), phospholipids (124 mg/dl) and free fatty acids (303 μequiv./l) were generally decreased. A disturbance of lipid absorption due to a defect of chylomicron formation and hepatic steatosis were also disclosed. On lipoprotein electrophoresis, prebetalipoprotein was very faint and migrated more slowly than normal. Betalipoprotein and alpha-lipoprotein were moderately reduced in concentration but migrated normally. The concentration of isolated VLDL was only one-tenth of that in normal subjects and it migrated as slow prebetalipoprotein. Although the lipid composition of VLDL was similar to that of normal VLDL, the lack of minor components was disclosed by SDS-PAG electrophoresis. Incorporation of [1- 14 C]acetate into VLDL lipids was significantly reduced to a greater extent than that of LDL and HDL. From these findings, we discuss the possibility that hypobetalipoproteinemia results from impaired VLDL synthesis.