Clinical Characterization of a Case with Familial Hypobetalipoproteinemia Caused by Apo B-76, a New Truncation of Apolipoprotein B, Combined with Apo E2/E2 Phenotype

We report a 43-year-old Japanese man with hypobetalipoproteinemia likely due to apolipoprotein (apo) B-76, a new truncation of apo B, and with homozygousity for the apo E2 isoform. He had no history suggestive of fat malabsorption and no sign of neurological disorder. His fasting baseline serum low-density lipoprotein (LDL) cholesterol and apo B levels were approximately half of normal. His plasma apo E level was elevated and its phenotype showed the E2/E2 homozygote. SDS-polyacrylamide gel electrophoresis of delipidated LDL fraction revealed a new truncated apo B, designated as apo B-76 according to the centile system of nomenclature. The postprandial lipid metabolism of the patient showed an almost normal response after fat loading.