Development of a new expanded next-generation sequencing panel for genetic diseases involved in dyslipidemia.

The aim of this study was to provide an efficient tool: reliable, able to increase the molecular diagnosis performance, to facilitate the detection of copy number variants (CNV), to assess genetic risk scores (wGRS) and to offer the opportunity to explore candidate genes. Custom SeqCap EZ libraries, NextSeq500 sequencing and a homemade pipeline enable the analysis of 311 dyslipidemia-related genes. In the training group (48 DNA from patients with a well-established molecular diagnosis), this next-generation sequencing (NGS) workflow showed an analytical sensitivity >99% (n = 532 variants) without any false negative including a partial deletion of one exon.

Involvement of a homozygous exon 6 deletion of LMF1 gene in intermittent severe hypertriglyceridemia.

Severe hypertriglyceridemia (HTG), characterized by triglycerides (TG) permanently over 10 mmol/L, may correspond to familial chylomicronemia syndrome (FCS), a rare disorder. However, hypertriglyceridemic patients more often present multifactorial chylomicronemia syndrome (MCS), characterized by highly variable TG. A few nonsense variants of LMF1 gene were reported in literature in FCS patients.

Characterisation of patients with familial chylomicronaemia syndrome (FCS) and multifactorial chylomicronaemia syndrome (MCS): Establishment of an FCS clinical diagnostic score.

Data presented in this article are supplementary material to our article entitled "Identification and diagnosis of patients with familial chylomicronaemia syndrome (FCS): expert panel recommendations and proposal of an "FCS Score" (Moulin et al., 2018, in press). The data describe the genotypes of patients with familial chylomicronaemia syndrome (FCS) and multifactorial chylomicronaemia syndrome (MCS), from the validation and replication cohorts.

New rare genetic variants of LMF1 gene identified in severe hypertriglyceridemia.

Background: The LMF1 (lipase maturation factor 1) gene encodes a protein involved in lipoprotein lipase and hepatic lipase maturation. Homozygous mutations in LMF1 leading to severe hypertriglyceridemia (SHTG) are rare in the literature. A few additional rare LMF1 variants have been described with poor functional studies.

Efficacy of two vitamin E formulations in patients with abetalipoproteinemia and chylomicron retention disease.

Abetalipoproteinemia (ABL) and chylomicron retention disease (CMRD) are extremely rare recessive forms of hypobetalipoproteinemia characterized by intestinal lipid malabsorption and severe vitamin E deficiency. Vitamin E is often supplemented in the form of fat-soluble vitamin E acetate, but fat malabsorption considerably limits correction of the deficiency. In this crossover study, we administered two different forms of vitamin E, tocofersolan (a water-soluble derivative of RRR-α-tocopherol) and α-tocopherol acetate, to three patients with ABL and four patients with CMRD.

Identification and diagnosis of patients with familial chylomicronaemia syndrome (FCS): Expert panel recommendations and proposal of an "FCS score".

Familial chylomicronaemia syndrome (FCS) is a rare, inherited disorder characterised by impaired clearance of triglyceride (TG)-rich lipoproteins from plasma, leading to severe hypertriglyceridaemia (HTG) and a markedly increased risk of acute pancreatitis. It is due to the lack of lipoprotein lipase (LPL) function, resulting from recessive loss of function mutations in the genes coding LPL or its modulators. A large overlap in the phenotype between FCS and multifactorial chylomicronaemia syndrome (MCS) contributes to the inconsistency in how patients are diagnosed and managed worldwide, whereas the incidence of acute hypertriglyceridaemic pancreatitis is more frequent in FCS.

Single, short in-del, and copy number variations detection in monogenic dyslipidemia using a next-generation sequencing strategy.

Optimal molecular diagnosis of primary dyslipidemia is challenging to confirm the diagnosis, test and identify at risk relatives. The aim of this study was to test the application of a single targeted next-generation sequencing (NGS) panel for hypercholesterolemia, hypocholesterolemia, and hypertriglyceridemia molecular diagnosis. NGS workflow based on a custom AmpliSeq panel was designed for sequencing the most prevalent dyslipidemia-causing genes (ANGPTL3, APOA5, APOC2, APOB, GPIHBP1, LDLR, LMF1, LPL, PCSK9) on the Ion PGM Sequencer.

Alterations in plasma triglycerides lipolysis in patients with history of multifactorial chylomicronemia.

Background And Aims: The heterogeneity and mechanisms of multifactorial chylomicronemia (MCM) remain poorly understood. To gain new insights, post heparin lipolysis measured at 60 min (PHLA60), in addition to the more commonly used 10 min (PHLA10), was assessed in patients with history of MCM.

Methods: 62 consecutive MCM patients were studied.

Circulating Klotho Associates With Cardiovascular Morbidity and Mortality During Hemodialysis.

Background: Klotho gene was identified as an aging suppressor. In animals, klotho overexpression extends life span, and defective klotho results in rapid aging and early death. The kidney is the main contributor to circulating klotho levels, and, during chronic kidney disease, renal klotho gene expression is drastically reduced in animals and humans as well.

Lack of evidence for a liver or intestinal miRNA regulation involved in the hypertriglyceridemic effect of APOC3 3'UTR variant SstI.

Background And Aims: APOC3 is a major regulator of triglycerides metabolism. Several APOC3 variants are associated with hypertriglyceridemia (HTG). Our aim was to establish the potential regulation of APOC3 3'UTR variants associated with HTG by liver or intestinal miRNAs.

Multiple microRNA regulation of lipoprotein lipase gene abolished by 3'UTR polymorphisms in a triglyceride-lowering haplotype harboring p.Ser474Ter.

Background: Lipoprotein lipase (LPL) is a key enzyme in triglyceride (TG) metabolism. LPL gene single nucleotide polymorphisms (SNPs) are associated with TG concentrations however the functionality of many of these SNPs remains poorly understood. MicroRNAs (miR) exert post-transcriptional down-regulation and their target sequence on the 3'UTR may be altered by SNPs.

Post-heparin LPL activity measurement using VLDL as a substrate: a new robust method for routine assessment of plasma triglyceride lipolysis defects.

Background: Determination of lipoprotein lipase (LPL) activity is important for hyperchylomicronemia diagnosis, but remains both unreliable and cumbersome with current methods. Consequently by using human VLDL as substrate we developed a new LPL assay which does not require sonication, radioactive or fluorescent particles.

Methods: Post-heparin plasma was added to the VLDL substrate prepared by ultracentrifugation of heat inactivated normolipidemic human serums, diluted in buffer, pH 8.

Post-heparin LPL activity measurement using VLDL as a substrate: a new robust method for routine assessment of plasma triglyceride lipolysis defects.

Background: Determination of lipoprotein lipase (LPL) activity is important for hyperchylomicronemia diagnosis, but remains both unreliable and cumbersome with current methods. Consequently by using human VLDL as substrate we developed a new LPL assay which does not require sonication, radioactive or fluorescent particles.

Methods: Post-heparin plasma was added to the VLDL substrate prepared by ultracentrifugation of heat inactivated normolipidemic human serums, diluted in buffer, pH 8.

An APOA5 3' UTR variant associated with plasma triglycerides triggers APOA5 downregulation by creating a functional miR-485-5p binding site.

APOA5 c.*158C>T (rs2266788), located in the 3' UTR, belongs to APOA5 haplotype 2 (APOA5*2), which is strongly associated with plasma triglyceride levels and modulates the occurrence of both moderate and severe hypertriglyceridemia. Individuals with APOA5*2 display reduced APOA5 expression at the posttranscriptional level.

GPIHBP1 C89F neomutation and hydrophobic C-terminal domain G175R mutation in two pedigrees with severe hyperchylomicronemia.

Context: GPIHBP1 is a new endothelial binding site for lipoprotein lipase (LPL), the key enzyme for intravascular lipolysis of triglyceride-rich lipoproteins (TGRL). We have identified two new missense mutations of the GPIHBP1 gene, C89F and G175R, by systematic sequencing in a cohort of 376 hyperchylomicronemic patients without mutations on the LPL, APOC2, or APOA5 gene.

Objective: Phenotypic expression and functional consequences of these two mutations were studied.

Quantitative loss of heterozygosity analysis for urothelial carcinoma detection and prognosis.

Objectives: To evaluate loss of heterozygosity (LOH) using microsatellite polymorphism analysis as a diagnostic and prognostic marker at the time of transurethral resection and as a follow-up marker preceding cystoscopic evidence of recurrence compared with cytology.

Methods: A total of 127 urothelial carcinoma (UC) patients were included. Tumors were staged and graded according to the International Union Against Cancer-tumor, node, metastases system and to the 2004 World Health Organization classification.

Prevalence and function of anti-lipoprotein lipase auto-antibodies in type V hyperchylomicronemia.

Purpose: Type V hyperlipidemia (HTG V) characterized by accumulation of both chylomicrons and VLDL results from a complex combination of genetic and environmental factors. However, a large proportion of sporadic cases remains largely unexplained. In a few cases, in a context of autoimmunity, auto-antibodies inhibiting lipoprotein lipase (LPL) activity have been incriminated.

Modulation of phenotypic expression of APOA5 Q97X and L242P mutations.

Objective: To provide phenotypic and functional data in new patients with APOA5 mutations and to identify genetic and metabolic factors influencing their phenotypic expression.

Methods And Results: By sequencing APOA5 gene in a cohort of 286 hyperchylomicronemic subjects, free of LPL or APOC2 mutations, we identified 4 unrelated carriers of the Q97X mutation (3 heterozygotes and 1 homozygote) and one heterozygote with a new L242P mutation. Postheparin LPL activity level was reduced by about 50% in Q97X heterozygotes and more than 90% in the Q97X homozygote, but was normal in the L242P patient after resolution of hyperchylomicronemia.

Association of APOA5 -1131T>C and S19W gene polymorphisms with both mild hypertriglyceridemia and hyperchylomicronemia in type 2 diabetic patients.

Background: Two minor apolipoprotein A5 (APOA5) gene haplotypes, represented by -1131T>C and S19W polymorphisms, are strong determinants of plasma triglyceride (TG) concentration variability across human populations. Hypertriglyceridemia is frequent in type 2 diabetes (T2D) and hyperchylomicronemia is not uncommon.

Methods: We investigated the association of -1131T>C and S19W polymorphisms with diabetic dyslipidemia in 400 Caucasian T2D patients divided in 2 groups: group N with 130 normotriglyceridemics (TG<90th percentile) and group M with 270 moderately hypertriglyceridemics.

Apoa5 Q139X truncation predisposes to late-onset hyperchylomicronemia due to lipoprotein lipase impairment.

While type 1 hyperlipidemia is associated with lipoprotein lipase or apoCII deficiencies, the etiology of type 5 hyperlipidemia remains largely unknown. We explored a new candidate gene, APOA5, for possible causative mutations in a pedigree of late-onset, vertically transmitted hyperchylomicronemia. A heterozygous Q139X mutation in APOA5 was present in both the proband and his affected son but was absent in 200 controls.

Combination of circulating antilipoprotein lipase (Anti-LPL) antibody and heterozygous S172 fsX179 mutation of LPL gene leading to chronic hyperchylomicronemia.

Context: Sporadic hyperchylomicronemia (type V hyperlipoproteinemia) results from complex interactions between genetic and environmental factors that often remain unknown.

Design: Upon investigation of a patient suffering from recurrent hypertriglyceridemic pancreatitis without family history or conventional secondary cause of dyslipidemia, we identified a previously unreported nonsense heterozygous lipoprotein lipase (LPL) gene mutation S172fsX179 associated with an antihuman LPL IgG.

Results: This autoantibody partially inhibited wild-type LPL activity in vitro.

Acid sphingomyelinase: identification of nine novel mutations among Italian Niemann Pick type B patients and characterization of in vivo functional in-frame start codon.

Niemann Pick disease (NPD) is an autosomal recessive disorder due to the deficit of lysosomal acid sphingomyelinase, which results in intracellular accumulation of sphingomyelin. In the present work we studied 18 patients with NPD type B, including five individuals who presented an intermediate phenotype characterised by different levels of neurological involvement. We identified nine novel mutations in the SMPD1 gene including six single base changes c.

[Familial hyperchylomicronemia with a new mutation of the lipoprotein lipase gene].

Introduction: Familial hyperchylomicronemia is a rare autosomal recessive disease caused by lipoprotein lipase deficiency.

Case-report: A nine month-old girl presented with eruptive xanthomas revealing a familial hyperchylomicronemia. No lipoprotein lipase activity was found.

Niemann-Pick C1 disease: correlations between NPC1 mutations, levels of NPC1 protein, and phenotypes emphasize the functional significance of the putative sterol-sensing domain and of the cysteine-rich luminal loop.

To obtain more information of the functional domains of the NPC1 protein, the mutational spectrum and the level of immunoreactive protein were investigated in skin fibroblasts from 30 unrelated patients with Niemann-Pick C1 disease. Nine of them were characterized by mild alterations of cellular cholesterol transport (the "variant" biochemical phenotype). The mutations showed a wide distribution to nearly all NPC1 domains, with a cluster (11/32) in a conserved NPC1 cysteine-rich luminal loop.

Ex vivo measurement of lipoprotein lipase-dependent very low density lipoprotein (VLDL)-triglyceride hydrolysis in human VLDL: an alternative to the postheparin assay of lipoprotein lipase activity?

The plasma lipolysis of triglyceride (TG)-rich lipoproteins is mainly due to the activity of lipoprotein lipase (LPL). Albeit important for our analysis of certain physiopathological situations, the determination of the magnitude of LPL-dependent lipolysis is not easy to perform. This essentially results from the binding of LPL to the luminal surface of vascular endothelium.