A heterozygous mutation (the codon for Ser447----a stop codon) in lipoprotein lipase contributes to a defect in lipid interface recognition in a case with type I hyperlipidemia.

Previously, we reported a case with type I hyperlipidemia due to a lipid interface recognition deficiency in lipoprotein lipase (LPL) (1). The LPL from postheparin plasma of this patient did not hydrolyze TritonX-100-triolein or very low density lipoprotein-triolein but did hydrolyze tributyrin and LysoPC-triolein substrates. Sequence analysis of the probands DNA revealed a heterozygous nucleotide change: a C----G transversion at position of 1595, resulting in changing the codon for Ser447 to a stop codon. Expression studies of this mutant LPLcDNA in Cos-1 cells produced and secreted considerable amounts of LPL mass in the culture media. The mutated LPL hydrolyzed much less TritonX-100-triolein than wild type LPL, whereas hydrolysis of tributyrin and LysoPC--triolein was the same with both the mutant and wild type LPL. These results suggest that this mutation might be responsible for the property of the LPL with a defect in lipid interface recognition in the type I patient we reported.