HYPOBETALIPOPROTEINEMIA ASSOCIATED WITH APO B-48.4, A TRUNCATED PROTEIN ONLY 14 AMINO-ACIDS LONGER THAN APO B-48

Familial hypobetalipoproteinemia is an autosomal codominant trait that can be caused by mutations in the apo B gene. Here we report a novel apo B gene mutation causing hypobetalipoproteinemia, that is associate d with the synthesis of a truncated apo B protein in a young healthy m ale subject and his mother. The mutation is an A deletion at position 6627 of the apo B cDNA leading to a truncated protein of 2166 amino ac ids (apo B-48.4). This truncated apo B was detected mainly in VLDL, LD L and in trace amounts in HDL, but not in the lipoprotein deficient pl asma fraction. Affected family members present with elevated levels of HDL-cholesterol, mainly due to an increase in HDL, particles. Postpra ndial triglycerides and retinyl esters in the d < 1.006 g/ml lipoprote in in the proband showed a normal response to an oral fat load compare d to a group of eight matched healthy controls. In summary this novel mutation is associated with hypobetalipoproteinemia with a normal fat absorption as expected for a protein with a length similar to that of apo B-48. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.