A novel apolipoprotein E5 variant with a 24-bp insertion causing hyperlipidemia

A tandem 24-bp insertion in the apolipoprotein E (apo E) gene was detected in a patient with elevated triglyceride, apolipoprotein (apo) CII and apo C III levels. This novel variant, apo E5ss, showed in position apo E5 by isoe lectric focusing and was of larger molecular weight than apo E3 during two- dimensional gel electrophoresis. Polymerase chain reaction-single strand co nformation polymorphism analysis using the primer pairs that cover all the coding regions was useful for rapid detection of the variant of the apo E a llele. Apo E5ss may have a 24-bp insertion caused by slipped mispairing, re sulting in a tandem duplication of amino acid residues 135-142 [APOE, 24-BP INS, DUP CODONS 135-142]. The proband was the only person with apo E5ss am ong the 806 Japanese males that we examined. We inspected six other reporte d apo E5 variants in the literature.