Clinical features and functions of a novel Lpl mutation C.986A>C (p.Y329S) in patient with hypertriglyceridemia

Abstract

Objective: To investigate and assess the clinical features and functions of a new lipoprotein lipase (Lpl) gene mutation c.986A>C (p.Y329S) found in hypertriglyceridemia(HTG) patients from a Chinese family.

Methods: Five members of a family with the proband were diagnosed with HTG were investigated, and fasting peripheral blood was collected . The plasma was then used to measure triglycerides (TG), total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein cholesterol (HDL-C), free fatty acids (FFA), and glucose tolerance. Following that, genomic deoxyribonucleic acid (DNA) was extracted from whole-blood samples using the QIAamp whole-blood DNA kit, and the coding exon regions and flanking regions of 95 dyslipidemia-related genes were captured using GenCap liquid-phase target gene capture technology. The activity of LPL and its mutation were then determined using cell assays, and the newly discovered LPL mutant was functionally analyzed. The binding site of fenofibrate and LPL, as well as the mutation, were subjected to predictive analysis.

Results: The LPL gene's c.986A>C (p.Y329S) heterozygous mutation was discovered, and patients with the mutation had the typical phenotype of LPL deficiency and weakened LPL activity. Furthermore, this mutant has been treated with fenofibrate, and its triglyceride level is perfectly controlled and stable. The prediction analysis of the fenofibrate and LPL binding sites reveals that the wild-type system, Phe378 contributes most to the binding energy of fenofibrate. In the mutant system, Tyr394, which contributes the most to the binding energy of fenofibrate, the contribution of S329 is greater than that of Y329 (0.9∼0.7 kal/mol) . After Y329 is mutated, the hydrogen bond data of fenofibrate and LPL will also increase to quote H-bond diagrams.

Conclusions: A heterozygous mutation c.986A>C (p.Y329S) in exon 6 of Lpl gene occurs in the proband with familial HTG. Lpl c.986A>C (p.Y329S) mutation weakens the activity of the LPL, which may be the pathogenic mutation of HTG. In addition, The proband has been treated with fenofibrate and the triglyceride level is ideally controlled and stable. The prediction analysis of the fenofibrate and LPL binding site shows that the wild-type system, Phe378 contributes most to the binding energy of fenofibrate. In the mutant system, Tyr394, which contributes the most to the binding energy of fenofibrate, the contribution of S329 is greater than that of Y329 (0.9∼0.7 kal/mol). After Y329 is mutated, the hydrogen bond data of fenofibrate and LPL will also increase, which may be one of the reasons why the mutation has no effect on the therapeutic effect of fenofibrate.