ANGPTL3 Mutations in Unrelated Chinese Han Patients with Familial Hypercholesterolemia

Angiopoietin-Like Protein 3 (ANGPTL3) Modulates Lipoprotein Metabolism and Dyslipidemia

Dyslipidemia is characterized by increasing plasma levels of low-density lipoprotein-cholesterol (LDL-C), triglycerides (TGs) and TG-rich lipoproteins (TGRLs) and is a major risk factor for the development of atherosclerotic cardiovascular disorders (ASCVDs). It is important to understand the metabolic mechanisms underlying dyslipidemia to develop effective strategies against ASCVDs. Angiopoietin-like 3 (ANGPTL3), a member of the angiopoietin-like protein family exclusively synthesized in the liver, has been demonstrated to be a critical regulator of lipoprotein metabolism to inhibit lipoprotein lipase (LPL) activity. Genetic, biochemical, and clinical studies in animals and humans have shown that loss of function, inactivation, or downregulated expression of ANGPTL3 is associated with an obvious reduction in plasma levels of TGs, LDL-C, and high-density lipoprotein-cholesterol (HDL-C), atherosclerotic lesions, and the risk of cardiovascular events. Therefore, ANGPTL3 is considered an alternative target for lipid-lowering therapy. Emerging studies have focused on ANGPTL3 inhibition via antisense oligonucleotides (ASOs) and monoclonal antibody-based therapies, which have been carried out in mouse or monkey models and in human clinical studies for the management of dyslipidemia and ASCVDs. This review will summarize the current literature on the important role of ANGPTL3 in controlling lipoprotein metabolism and dyslipidemia, with an emphasis on anti-ANGPTL3 therapies as a potential strategy for the treatment of dyslipidemia and ASCVDs.

Whole exome sequencing for non-selective pediatric patients with hyperlipidemia

BACKGROUND

Hyperlipidemia is a group of conditions with abnormally elevated levels of any or all lipids or lipoproteins in the blood. It is highly heterogeneous both genetically and clinically, which contributes to diagnostic challenges and results in many patients to be underdiagnosed and undertreated in China. Precise diagnosis and early management are critical to reduce the incidence of potential coronary artery disease and cardiovascular disease.

RESULTS

We performed a single center study to demonstrate the clinical utility of the genome-first approach by whole exome sequencing (WES) for 12 pediatric patients with abnormal lipids or lipoproteins levels. In vitro experiments were performed in COS-7 cells to further evaluate the biological function of the novel variants. We identified ten pathogenic and likely pathogenic variants and three of them were novel. Molecular cause was uncovered in five (41.7%) patients including three lipoprotein lipase deficiency patients, one hypercholesterolemia patient and one sitosterolemia patient. We also found three patients with rare variants of uncertain significance. Copy number variant (CNV) analysis with WES data did not reveal any potential hyperlipidemia related CNVs in all patients.

CONCLUSION

We expanded the mutation and phenotype spectra of familial hyperlipidemia. Our study demonstrated the effectiveness of genome-first approach for evaluation pediatric hyperlipidemia patients and showed that WES can be used as the first-tier test for patients with suspected Mendelian hyperlipidemia disorder.

Association study of genetic variants of the ANGPTL3 gene and susceptibility to ischemic stroke

BACKGROUND

Stroke ranks as the third-leading cause of years of life lost worldwide. ANGPTL3 plays important roles in lipid metabolism, atherosclerosis, and occurrence of stroke. The purpose of this study was to evaluate associations of genetic variants in the ANGPTL3 gene with ischemic stroke (IS) risk.

METHODS

A case-control study was conducted to evaluate the associations of tag single-nucleotide polymorphisms (SNPs) of the ANGPTL3 gene and risk of IS, as well as serum lipid levels. Dual-luciferase reporter assays in the HEK293T cell line was conducted to evaluate the promoter activity of ANGPTL3 rs6690733.

RESULTS

We found rs6690733 (C vs A: OR 1.34, 95% CI 1.13-1.59; P=0.001) and rs12563308 (C vs T: OR 0.77, 95% CI 0.64-0.93, P=0.007) were significantly associated with susceptibility to IS. Even corrected for Bonferroni adjustment, the two variants were still significant (0.007×4=0.028). Carriers of the minor allele of SNP rs6690733 had significantly higher levels of TC and LDL-C, while carriers of the minor allele of SNP rs12563308 had significantly lower levels of TC and LDL-C (all P<0.05). For rs6690733, the luciferase assay showed that promoter activity was significantly increased by 67% of plasmids containing the minor C allele compared with the major A allele in HEK293 cells.

CONCLUSION

Our study revealed genetic variants of the ANGPTL3 gene could contribute to susceptibility to IS through participating in the regulation of lipid metabolism.