Prevalence and predictive role of hypertriglyceridemia in statin-treated patients at very high risk: Insights from the START study

BACKGROUND AND AIM

Elevated triglyceride (TG) levels seem to identify subjects at increased cardiovascular risk, independent of LDL-C levels. We sought to evaluate the predictive role of hypertriglyceridemia, defined as TG levels ≥150 mg/dl, in very high risk (VHR) patients with chronic coronary syndromes (CCS) treated with statins.

METHODS AND RESULTS

Using the data from the STable Coronary Artery Diseases RegisTry (START) study, an Italian nationwide registry, we assessed the association between the TG levels and baseline clinical characteristics, pharmacological treatment and major adverse cardio-cerebrovascular events (MACCE) at 1 year in a large cohort of statin-treated patients at VHR. Of the 4751 consecutive patients with CCS enrolled in the registry and classified as VHR, 2652 (55.8%) had TG values available (mean 120.6 ± 54.9) and were treated with at least a statin at baseline: 2019 (76.1%) with TG < 150 and 633 (23.9%) with TG ≥ 150 mg/dl. At 1 year from enrolment, MACCE occurred in 168 (6.3%) patients, without differences between the two groups of TG (5.9 vs 7.6%; p = 0.14). At multivariable analysis, hypertriglyceridemia did not result as independent predictor of the MACCE (hazard ratio: 1.16; 95% confidence intervals: 0.82-1.64; p = 0.42).

CONCLUSIONS

In the present large, nationwide cohort of consecutive CCS patients at VHR with statin-controlled LDL-C levels, hypertriglyceridemia was present in around 24% of cases and did not result as predictor of MACCE at 1 year. Further studies with a longer follow-up and larger sample size are needed to better define the prognostic role of TG levels when intensive LDL lowering therapies are used.

Lack of phenotypic additive effect of familial defective apolipoprotein B3531 in familial hypercholesterolaemia

Familial defective apolipoprotein (apo) B (FDB) and familial hypercholesterolaemia (FH) are the two common genetic conditions that cause hypercholesterolaemia. R3531C mutation of the APOB gene is a rare cause of FDB. Individuals with both FDB and FH are rare. A 51-year-old man with hypercholesterolaemia (11.4 mmol/L) and his family were studied. Low-density lipoprotein (LDL) receptor (LDLR) and APOB genes were analysed by direct sequencing. LDL of four subjects were studied in a fibroblast LDL receptor-binding displacement assay. We found a mutation of the LDLR gene (p.Y398X) in the proband and in four other family members: the p.R3531C APOB gene mutation was also found in the proband, his father and his children. The proband and his son were thus compound heterozygotes for both FH and FDB. Double heterozygotes did not show higher cholesterol levels compared to carriers of LDLR gene mutation alone. LDL from one of the carriers of the p.R3531C alone exhibited a binding ability, which was similar to a normal subject. This is the first report in Italy of the p.R3531C mutation, and our results show that this mutation has no effect in LDLR p.Y398X/APOB p.R3531C double heterozygotes.

rs629301 CELSR2 polymorphism confers a ten-year equivalent risk of critical stenosis assessed by coronary angiography

BACKGROUND AND AIMS

Novel genetic determinants associated with coronary artery disease (CAD) have been discovered by genome wide association studies. Variants encompassing the CELSR2- PSRC1-SORT1 gene cluster have been associated with CAD. This study is aimed to investigate the rs629301 polymorphism association with the extent of CAD evaluated by coronary angiography (CAG), and to evaluate its associations with an extensive panel of lipid and lipoprotein measurements in a large Italian cohort of 2429 patients.

METHODS AND RESULTS

The patients were collected by four Intensive Care Units located in Palermo and Verona (Italy). Clinical Records were filed, blood samples were collected, lipids and apolipoproteins (apo) were measured in separate laboratories. CAD was defined by the presence of stenotic arteries (>50% lumen diameter) by CAG. The presence of CAD was associated with the rs629301 genotype. Patients with CAD were 78% and 73% (p = 0.007) of the T/T vs. T/G + G/G genotype carriers respectively. T/T genotype was also correlated with the number of stenotic arteries, with a 1.29 (1.04-1.61) risk to have a three-arteries disease. T/T genotype correlated with higher levels of LDL-, non-HDL cholesterol, apoB, apoE and apoCIII, and lower HDL-cholesterol. Logistic Regression confirmed that rs629301was associated with CAD independently from the common risk factors, with a risk similar to that conferred by ten years of age [odds ratios were 1.43 (1.04-1.96) and 1.39 (1.22-1.58) respectively].

CONCLUSIONS

rs629301 risk allele was independently associated with the extension and severity of CAD and positively with apoE and apoB containing lipoproteins.

DeepSRE: Identification of sterol responsive elements and nuclear transcription factors Y proximity in human DNA by Convolutional Neural Network analysis

SREBP1 and 2, are cholesterol sensors able to modulate cholesterol-related gene expression responses. SREBPs binding sites are characterized by the presence of multiple target sequences as SRE, NFY and SP1, that can be arranged differently in different genes, so that it is not easy to identify the binding site on the basis of direct DNA sequence analysis. This paper presents a complete workflow based on a one-dimensional Convolutional Neural Network (CNN) model able to detect putative SREBPs binding sites irrespective of target elements arrangements. The strategy is based on the recognition of SRE linked (less than 250 bp) to NFY sequences according to chromosomal localization derived from TF Immunoprecipitation (TF ChIP) experiments. The CNN is trained with several 100 bp sequences containing both SRE and NF-Y. Once trained, the model is used to predict the presence of SRE-NFY in the first 500 bp of all the known gene promoters. Finally, genes are grouped according to biological process and the processes enriched in genes containing SRE-NFY in their promoters are analyzed in details. This workflow allowed to identify biological processes enriched in SRE containing genes not directly linked to cholesterol metabolism and possible novel DNA patterns able to fill in for missing classical SRE sequences.

Therapeutic Options for Homozygous Familial Hypercholesterolemia: The Role of Lomitapide

Background:

Lomitapide (Juxtapid® in US and Lojuxta® in Europe) is the first developed inhibitor of the Microsomal Triglyceride Transfer Protein (MTP) approved as a novel drug for the management of Homozygous Familial Hypercholesterolemia (HoFH). It acts by binding directly and selectively to MTP thus decreasing the assembly and secretion of the apo-B containing lipoproteins both in the liver and in the intestine.

Aims:

The present review aims at summarizing the recent knowledge on lomitapide in the management of HoFH.

Results:

The efficacy and safety of lomitapide have been evaluated in several trials and it has been shown a reduction of the plasma levels of Low-Density Lipoprotein Cholesterol (LDL-C) by an average of more than 50%. Although the most common side effects are gastrointestinal and liver events, lomitapide presents generally with a good tolerability and satisfactory patients compliance. Recently, in Europe, to evaluate the long-term safety and efficacy of lomitapide, the LOWER registry (ClinicalTrials.gov Identifier: NCT02135705) has been established in order to acquire informations on HoFH lomitapidetreated patients from “real life” clinical practice.

:

Furthermore, the observation that lomitapide decreases triglyceride levels may be considered for patients affected by severe forms of hypertriglyceridemia who undergo recurrent episodes of pancreatitis and are poor responders to conventional treatment.

Conclusion:

Lomitapide represents an innovative and efficacious drug for the treatment of HoFH. Longterm safety data, treatment of pediatric and pregnant HoFH patients and management of severe hypertriglyceridemia still require further investigations.

Anti-PCSK9 treatment: is ultra-low low-density lipoprotein cholesterol always good?

Anti-PCSK9 (proprotein convertase subtilisin kexin 9) monoclonal antibodies (Mab) are novel, potent lipid-lowering drugs. They demonstrated to improve the lipid profile in high cardiovascular risk patients. Anti-PCSK9 Mab inhibit the targeted low-density lipoprotein (LDL)-receptor degradation induced by PCSK9 protein and are able to reduce LDL cholesterol (LDL-C) levels on top of conventional lipid-lowering therapy. Though these drugs proved to be very safe in the short-term, little is known about the possible long-term effects, due to the short period of their marketing. The genetic low cholesterol syndromes (LCS) represent the natural models of the lipid-lowering anti-PCSK9 therapy, and a valuable opportunity to predict the long-term effects of these drugs. By looking at the clinical features of such models, we could be able to foresee possible drug-induced side effects. In the present review, the correspondences and discordances between the side effects of anti-PCSK9 therapy and the corresponding LCS models will be examined in the attempt to forecast possible long-term consequences of these novel lipid-lowering agents.

Genetic epidemiology of autosomal recessive hypercholesterolemia in Sicily: Identification by next-generation sequencing of a new kindred

BACKGROUND

Autosomal recessive hypercholesterolemia (ARH) is a rare inherited lipid disorder. In Sardinia, differently from other world regions, the mutated allele frequency is high. It is caused by mutations in the low-density lipoprotein receptor adaptor protein 1 gene. Fourteen different mutations have been reported so far; in Sardinia, 2 alleles (ARH1 and ARH2) explain most of the cases. Four ARH patients, all carriers of the ARH1 mutation, have been identified in mainland Italy and 2 in Sicily.

OBJECTIVE

The objectives of the study were to improve the molecular diagnosis of familial hypercholesterolemia (FH) and to estimate the frequency of the ARH1 allele in 2 free-living Sicilian populations.

METHODS

We sequenced by targeted next-generation sequencing 20 genes related to low-density lipoprotein metabolism in 50 hypercholesterolemic subjects. Subjects from 2 free-living populations from Northern (Ventimiglia Heart Study, 848 individuals) and Southern Sicily (Zabut Zabùt Aging Project, 1717 individuals) were genotyped for ARH1 allele.

RESULTS

We identified 1 homozygous carrier of the ARH1 mutation among the 50 hypercholesterolemic outpatients. Population-based genotyping of ARH1 in 2565 subjects allowed the identification of 1 heterozygous carrier. The overall estimated allele frequency of ARH1 in Sicily was 0.0002 (0.02%).

CONCLUSIONS

The identification of a new case of ARH in Sicily among 50 clinically diagnosed FH highlights the importance of next-generation sequencing analysis as tool to improve the FH diagnosis. Our results also indicate that ARH1 carrier status is present in ∼1:2500 of Sicilian inhabitants, confirming that ARH is extremely rare outside Sardinia.

Threshold Effects of Circulating Angiopoietin-Like 3 Levels on Plasma Lipoproteins

CONTEXT

Angiopoietin-like 3 (ANGPTL3) deficiency in plasma due to loss-of-function gene mutations results in familial combined hypobetalipoproteinemia type 2 (FHBL2) in homozygotes. However, the lipid phenotype in heterozygotes is much milder and does not appear to relate directly to ANGPTL3 levels. Furthermore, the low-density lipoprotein (LDL) phenotype in carriers of ANGPTL3 mutations is unexplained.

OBJECTIVE

To determine whether reduction below a critical threshold in plasma ANGPTL3 levels is a determinant of lipoprotein metabolism in FHBL2, and to determine whether proprotein convertase subtilisin kexin type 9 (PCSK9) is involved in determining low LDL levels in this condition.

DESIGN

We studied subjects from 19 families with ANGPTL3 mutations and subjects with familial combined hypobetalipoproteinemia type 1 (FHBL1) due to truncated apolipoprotein B (apoB) species.

RESULTS

First, total cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, and HDL and LDL particle concentration correlated with plasma ANGPTL3 levels but only when the latter was <25% of normal (<60 ng/dL). Second, the very low-density lipoprotein particle concentration correlated strongly with plasma ANGPTL3 when the latter was <58% of normal. Third, both FHBL1 and FHBL2 subjects showed low levels of mature and LDL-bound PCSK9 and higher levels of its furin-cleaved form. Finally, LDL-bound PCSK9 is protected from cleavage by furin and binds to the LDL receptor more strongly than apoB-free PCSK9.

CONCLUSIONS

Our results suggest that the hypolipidemic effects of ANGPTL3 mutations in FHBL2 are dependent on a threshold of plasma ANGPTL3 levels, with differential effects on various lipoprotein particles. The increased inactivation of PCSK9 by furin in FHBL1 and FHBL2 is likely to cause increased LDL clearance and suggests novel therapeutic avenues.

Association between familial hypobetalipoproteinemia and the risk of diabetes. Is this the other side of the cholesterol-diabetes connection? A systematic review of literature

Statin therapy is beneficial in reducing LDL cholesterol (LDL-C) levels and cardiovascular events, but it is associated with the risk of incident diabetes mellitus (DM). Familial hypercholesterolemia (FH) is characterized by genetically determined high levels of plasma LDL-C and a low prevalence of DM. LDL-C levels seem then inversely correlated with prevalence of DM. Familial hypobetalipoproteinemia (FHBL) represents the genetic mirror of FH in terms of LDL-C levels, very low in subjects carrying mutations of APOB, PCSK9 (FHBL1) or ANGPTL3 (FHBL2). This review explores the hypothesis that FHBL might represent also the genetic mirror of FH in terms of prevalence of DM and that it is expected to be increased in FHBL in comparison with the general population. A systematic review of published literature on FHBL was made by searching PubMed (1980-2016) for articles presenting clinical data on FHBL probands and relatives. The standardized prevalence rates of DM in FHBL1 were similar to those of the reference population, with a prevalence rate of 8.2 and 9.2%, respectively, while FHBL2 showed a 4.9% prevalence of DM. In conclusion, low LDL-C levels of FHBL do not seem connected to DM as it happens in subjects undergoing statin therapy and the diabetogenic effect of statins has to be explained by mechanisms that do not rely exclusively on the reduced levels of LDL-C. The review also summarizes the published data on the effects of FHBL on insulin sensitivity and the relationships between FH, statin therapy, FHBL1 and intracellular cholesterol metabolism, evaluating possible diabetogenic pathways.

Identification of a novel LMF1 nonsense mutation responsible for severe hypertriglyceridemia by targeted next-generation sequencing

BACKGROUND

Severe hypertriglyceridemia (HTG) may result from mutations in genes affecting the intravascular lipolysis of triglyceride (TG)-rich lipoproteins.

OBJECTIVE

The aim of this study was to develop a targeted next-generation sequencing panel for the molecular diagnosis of disorders characterized by severe HTG.

METHODS

We developed a targeted customized panel for next-generation sequencing Ion Torrent Personal Genome Machine to capture the coding exons and intron/exon boundaries of 18 genes affecting the main pathways of TG synthesis and metabolism. We sequenced 11 samples of patients with severe HTG (TG>885 mg/dL-10 mmol/L): 4 positive controls in whom pathogenic mutations had previously been identified by Sanger sequencing and 7 patients in whom the molecular defect was still unknown.

RESULTS

The customized panel was accurate, and it allowed to confirm genetic variants previously identified in all positive controls with primary severe HTG. Only 1 patient of 7 with HTG was found to be carrier of a homozygous pathogenic mutation of the third novel mutation of LMF1 gene (c.1380C>G-p.Y460X). The clinical and molecular familial cascade screening allowed the identification of 2 additional affected siblings and 7 heterozygous carriers of the mutation.

CONCLUSIONS

We showed that our targeted resequencing approach for genetic diagnosis of severe HTG appears to be accurate, less time consuming, and more economical compared with traditional Sanger resequencing. The identification of pathogenic mutations in candidate genes remains challenging and clinical resequencing should mainly intended for patients with strong clinical criteria for monogenic severe HTG.

Baseline metabolic disturbances and the twenty-five years risk of incident cancer in a Mediterranean population

BACKGROUND AND AIMS

Obesity is predictive of metabolic syndrome (metS), type 2 diabetes, cardiovascular (CV) disease and cancer. The aim of the study is to assess the risk of incident cancer connected to obesity and metS in a Mediterranean population characterized by a high prevalence of obesity.

METHODS AND RESULTS

As many as 1133 subjects were enrolled in two phases and followed for 25 years (859 subjects) or 11 years (274 subjects) and incident cancer was registered in the follow-up period. Anthropometric measures and biochemical parameters were filed at baseline and evaluated as predictors of incident cancer by measuring hazards ratios (HR) using multivariate Cox parametric hazards models. Best predictive threshold for metabolic parameters and metS criteria were recalculated by ROC analysis. Fasting Blood Glucose >5.19 mmol/L [HR = 1.58 (1.0-2.4)] and the TG/HDL ratio (log₁₀) (Males > 0.225, Females > 0.272) [HR = 2.44 (1.3-4.4)] resulted independent predictors of survival free of cancer with a clear additive effect together with age classes [45-65 years, HR = 2.47 (1.3-4.4), 65-75 years HR = 3.80 (2.0-7.1)] and male gender [HR = 2.07 (2.3-3.1)].

CONCLUSIONS

Metabolic disturbances are predictive of cancer in a 25 years follow-up of a Mediterranean population following a traditional Mediterranean diet. The high prevalence of obesity and metS and the observed underlying condition of insulin resistance expose this population to an increased risk of cardiovascular disease and cancer despite the healthy nutritional habits.

Myristic acid is associated to low plasma HDL cholesterol levels in a Mediterranean population and increases HDL catabolism by enhancing HDL particles trapping to cell surface proteoglycans in a liver hepatoma cell model

BACKGROUND

HDL-C plasma levels are modulated by dietary fatty acid (FA), but studies investigating dietary supplementation in FA gave contrasting results. Saturated FA increased HDL-C levels only in some studies. Mono-unsaturated FA exerted a slight effect while poly-unsaturated FA mostly increased plasma HDL-C.

AIMS

This study presents two aims: i) to investigate the relationship between HDL-C levels and plasma FA composition in a Sicilian population following a "Mediterranean diet", ii) to investigate if FA that resulted correlated with plasma HDL-C levels in the population study and/or very abundant in the plasma were able to affect HDL catabolism in an "in vitro" model of cultured hepatoma cells (HepG2).

RESULTS

plasma HDL-C levels in the population correlated negatively with myristic acid (C14:0, β = -0.24, p < 0.01), oleic acid (C18:1n9, β = -0.22, p < 0.01) and cis-11-Eicosenoic (C20:1n9, β = -0.19, p = 0.01) and positively with palmitoleic acid (C16:1, β = +0.19, p = 0.03). HepG2 cells were conditioned with FA before evaluating HDL binding kinetics, and only C14:0 increased HDL binding by a non-saturable pathway. After removal of heparan sulphate proteoglycans (HSPG) by heparinases HDL binding dropped by 29% only in C14:0 conditioned cells (p < 0.05). C14:0 showed also the highest internalization of HDL-derived cholesteryl esters (CE, +32% p = 0.01 vs. non-conditioned cells).

CONCLUSIONS

C14:0 was correlated with decreased plasma HDL-C levels in a Mediterranean population. C14:0 might reduce HDL-C levels by increasing HDL trapping to cell surface HSPG and CE stripping from bound HDL. Other mechanisms are to be investigated to explain the effects of other FA on HDL metabolism.

Novel CREB3L3 Nonsense Mutation in a Family With Dominant Hypertriglyceridemia

OBJECTIVE

Cyclic AMP responsive element-binding protein 3-like 3 (CREB3L3) is a novel candidate gene for dominant hypertriglyceridemia. To date, only 4 kindred with dominant hypertriglyceridemia have been found to be carriers of 2 nonsense mutations in CREB3L3 gene (245fs and W46X). We investigated a family in which hypertriglyceridemia displayed an autosomal dominant pattern of inheritance.

APPROACH AND RESULTS

The proband was a 49-year-old woman with high plasma triglycerides (≤1300 mg/dL; 14.68 mmol/L). Her father had a history of moderate hypertriglyceridemia, and her 51-year-old brother had triglycerides levels as high as 1600 mg/dL (18.06 mmol/L). To identify the causal mutation in this family, we analyzed the candidate genes of recessive and dominant forms of primary hypertriglyceridemia by direct sequencing. The sequencing of CREB3L3 gene led to the discovery of a novel minute frame shift mutation in exon 3 of CREB3L3 gene, predicted to result in the formation of a truncated protein devoid of function (c.359delG-p.K120fsX20). Heterozygosity for the c.359delG mutation resulted in a severe phenotype occurring later in life in the proband and her brother and a good response to diet and a hypotriglyceridemic treatment. The same mutation was detected in a 13-year-old daughter who to date is normotriglyceridemic.

CONCLUSIONS

We have identified a novel pathogenic mutation in CREB3L3 gene in a family with dominant hypertriglyceridemia with a variable pattern of penetrance.

Clinical experience of lomitapide therapy in patients with homozygous familial hypercholesterolaemia

The microsomal triglyceride transfer protein (MTP) inhibitor lomitapide is a licenced adjunct to a low-fat diet and other lipid-lowering medication, with or without low-density lipoprotein apheresis, for the treatment of adults with homozygous familial hypercholesterolaemia (HoFH). In a recently published phase 3 study, patients with HoFH received lomitapide in addition to maximally tolerated lipid-lowering therapy. Treatment with lomitapide resulted in a mean approximate 50% reduction in LDL-C levels after 26 weeks compared with baseline levels (p < 0.0001). This decrease in LDL-C was maintained at Weeks 56 and 78 (44% [p < 0.0001] and 38% [p = 0.0001], respectively). This paper offers clinical perspectives based on selected case histories of patients participating in the phase 3 lomitapide study. These cases provide illustrative examples of the efficacy of lomitapide, with or without apheresis, and show that the effective management of adverse effects can enable patients to remain on effective treatment.

Role of Nutraceuticals in Hypolipidemic Therapy

Nutraceuticals are food components or active ingredients present in foods and used in therapy. This article analyzes the characteristics of the molecules with a lipid-lowering effect. The different nutraceuticals may have different mechanisms of action: inhibition of cholesterol synthesis primarily through action on the enzyme HMG-CoA reductase (policosanol, polyphenols, garlic and, above all, red yeast rice), increase in LDL receptor activity (berberine), reduction of intestinal cholesterol absorption (garlic, plant sterols, probiotics), and also the ability to interfere with bile metabolism (probiotics, guggul). Based on the different mechanisms of action, some nutraceuticals are then able to enhance the action of statins. Nutraceuticals are often used without relevant evidence: mechanisms of action are not clearly confirmed; most of clinical data are derived from small, uncontrolled studies, and finally, except for fermented red rice, there are no clinical trials which may document the relationship between these interventions and the reduction of clinical events. Therefore, among all nutraceuticals, it is necessary to extrapolate those having a really documentable efficacy. However, these kinds of treatments are usually well-tolerated by patients. Overall, subjects with a middle or low cardiovascular risk are the best indication of nutraceuticals, but they may also be useful for patients experiencing side effects during classical therapies. Finally, in consideration of the additive effect of some nutraceuticals, a combination therapy with classical drugs may improve the achievement of clinical targets. Thus, nutraceuticals may be a helpful alternative in hypolipidemic treatment and, if properly used, might represent a valid strategy of cardiovascular prevention.

The pathophysiology of intestinal lipoprotein production

Intestinal lipoprotein production is a multistep process, essential for the absorption of dietary fats and fat-soluble vitamins. Chylomicron assembly begins in the endoplasmic reticulum with the formation of primordial, phospholipids-rich particles that are then transported to the Golgi for secretion. Several classes of transporters play a role in the selective uptake and/or export of lipids through the villus enterocytes. Once secreted in the lymph stream, triglyceride-rich lipoproteins (TRLs) are metabolized by Lipoprotein lipase (LPL), which catalyzes the hydrolysis of triacylglycerols of very low density lipoproteins (VLDLs) and chylomicrons, thereby delivering free fatty acids to various tissues. Genetic mutations in the genes codifying for these proteins are responsible of different inherited disorders affecting chylomicron metabolism. This review focuses on the molecular pathways that modulate the uptake and the transport of lipoproteins of intestinal origin and it will highlight recent findings on TRLs assembly.

Exome sequencing in suspected monogenic dyslipidemias

BACKGROUND

Exome sequencing is a promising tool for gene mapping in Mendelian disorders. We used this technique in an attempt to identify novel genes underlying monogenic dyslipidemias.

METHODS AND RESULTS

We performed exome sequencing on 213 selected family members from 41 kindreds with suspected Mendelian inheritance of extreme levels of low-density lipoprotein cholesterol (after candidate gene sequencing excluded known genetic causes for high low-density lipoprotein cholesterol families) or high-density lipoprotein cholesterol. We used standard analytic approaches to identify candidate variants and also assigned a polygenic score to each individual to account for their burden of common genetic variants known to influence lipid levels. In 9 families, we identified likely pathogenic variants in known lipid genes (ABCA1, APOB, APOE, LDLR, LIPA, and PCSK9); however, we were unable to identify obvious genetic etiologies in the remaining 32 families, despite follow-up analyses. We identified 3 factors that limited novel gene discovery: (1) imperfect sequencing coverage across the exome hid potentially causal variants; (2) large numbers of shared rare alleles within families obfuscated causal variant identification; and (3) individuals from 15% of families carried a significant burden of common lipid-related alleles, suggesting complex inheritance can masquerade as monogenic disease.

CONCLUSIONS

We identified the genetic basis of disease in 9 of 41 families; however, none of these represented novel gene discoveries. Our results highlight the promise and limitations of exome sequencing as a discovery technique in suspected monogenic dyslipidemias. Considering the confounders identified may inform the design of future exome sequencing studies.

Homozygous familial hypobetalipoproteinemia: two novel mutations in the splicing sites of apolipoprotein B gene and review of the literature

OBJECTIVE

Familial hypobetalipoproteinemia (FHBL) is autosomal codominant disorder of lipoprotein metabolism characterized by low plasma levels of total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C) and apolipoprotein B (apoB) below the 5(th) percentile of the distribution in the population. Patients with the clinical diagnosis of homozygous FHBL (Ho-FHBL) are extremely rare and few patients have been characterized at the molecular level. Here we report the medical history and the molecular characterization of one paediatric patient with clinical features of Ho-FHBL.

METHODS

A one month old infant with failure to thrive, severe hypocholesterolemia and acanthocytosis was clinically and genetically characterized. Molecular characterization of the proband and her parents was performed by direct sequencing of the APOB gene and functional role of the identified mutations was assessed by the minigene methodology.

RESULTS

The proband was found carrying two novel splicing mutations of the APOB gene (c.3696+1G > C and c.3697-1G > A). CHOK1H8 cells expressing minigenes harbouring the mutations showed that these two mutations were associated with the retention of intron 23 and skipping of exon 24, resulting in two truncated apoB fragments of approximate size of 26-28 % of ApoB-100 and the total absence of apoB.

CONCLUSION

We describe the first case of Ho-FHBL due to two splicing mutations affecting both the donor and the acceptor splice sites of the same intron of the APOB gene occurring in the same patient. The clinical management of the proband is discussed and a review of the clinical and genetic features of the published Ho-FHBL cases is reported.

Beyond statins: new lipid lowering strategies to reduce cardiovascular risk

Statins are the first-line therapy in LDL-Cholesterol (LDL-C) reduction and its clinical use has contributed to significant prevention and treatment of atherosclerotic vascular disease. Yet, a significant proportion of patients remain at high risk. Recently, a number of new therapies have been developed to further lower LDL-C. These agents may provide clinical benefit on top of statin therapy in patients with high residual risk, severe hypercholesterolemia or as an alternative for patients who are intolerant to statins. We review four novel approaches based on the inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9), apolipoprotein-B100 (apoB), Cholesteryl ester transport protein (CETP) and microsomal triglyceride transfer protein (MTP). ApoB and MTP inhibitors (Mipomersen and Lomitapide) are indicated only for homozygous familial hypercholesterolemia patients. The results of ongoing trials with CETP and PCSK9 inhibitors may warrant a wider employment in different categories of patients at high risk for cardiovascular disease.

Gelatinases and their tissue inhibitors in a group of subjects with metabolic syndrome

AIM

To evaluate matrix metalloproteases (MMP)-2 and MMP-9 and tissue inhibitor of metalloproteases (TIMP)-1 and TIMP-2 in a group of subjects with metabolic syndrome (MS) subdivided according to the presence or absence of diabetes mellitus.

METHODS

We examined in 90 subjects (51 men and 39 women) with MS, defined following the International Diabetes Federation criteria, and subsequently subdivided into diabetic subjects (22 men and 11 women) and nondiabetic subjects s (29 men and 28 women), the plasma concentrations of MMP-2 and MMP-9 and of TIMP-1 and TIMP-2 using specific enzyme-linked immunosorbent assay kits.

RESULTS

We found a significant increase in plasma concentrations of MMP-2, MMP-9, TIMP-1, and TIMP-2 in the whole group of MS subjects (P < 0.001) and in both subgroups of MS subjects with diabetes mellitus (P < 0.001) and without diabetes mellitus (P < 0.001) in comparison with healthy controls. We also noted higher concentrations of all the examined parameters in the MS subjects with diabetes mellitus in comparison with the MS subjects without diabetes mellitus. Matrix metalloproteases and TIMPs showed some significant correlations with body mass index and waist circumference and with metabolic parameters in the whole group of MS subjects.

CONCLUSION

An altered pattern of MMPs and their inhibitors is demonstrated in MS; the presence of diabetes mellitus strongly influences the concentration of MMP and TIMP, contributing probably to the increased cardiovascular risk of MS subjects.

Behavior of the total antioxidant status in a group of subjects with metabolic syndrome

AIMS

Our purpose was to examine the total antioxidant status (TAS) in subjects with metabolic syndrome (MS) subdivided according to the presence or not of diabetes mellitus.

METHODS

We enrolled 106 subjects (45 women, 61 men) with MS subsequently subdivided in diabetics (14 women, 29 men) and nondiabetics (31 women, 29 men). TAS was obtained using an Assay kit which relies on the ability of plasma antioxidant substances to inhibit the oxidation of 2,2'-azino-bis(3-ethylbenzthiazoline sulfonic acid) to the radical ABTS·+.

RESULTS

In the group of MS subjects a significant decrease in TAS (p<0.05) in comparison with normal controls was evident. This difference was present between normal subjects and nondiabetic subjects with MS (p<0.001) but not between normal and diabetic subjects with MS. Examining the linear regression among TAS, age, anthropometric profile, blood pressure values and glycometabolic pattern, conflicting data were found.

CONCLUSIONS

Although we know that TAS includes several enzymatic and non enzymatic antioxidants, we retain that the difference observed in the two subgroups of subjects with MS must be looked in particular into two pathophysiological aspects regarding bilirubin and uric acid.

The atrial natriuretic peptide genetic variant rs5068 is associated with a favorable cardiometabolic phenotype in a Mediterranean population

OBJECTIVE

We hypothesized that the minor allele of the atrial natriuretic peptide (ANP) genetic variant rs5068 is associated with a favorable cardiometabolic phenotype in a general Mediterranean population.

RESEARCH DESIGN AND METHODS

We genotyped a random sample of the residents of Ventimiglia di Sicilia, Sicily, for rs5068.

RESULTS

Genotype frequencies of rs5068 are AA, 93.5%; AG, 6.4%; and GG, 0.1%. All subsequent analyses are AA versus AG+GG. After adjusting for age and sex, the minor G allele is associated with lower BMI (estimate [SE]: -1.7 kg/m(2) [0.8], P = 0.04). In the AG+GG group, males with HDL cholesterol levels <40 mg/dL are less frequent (P = 0.05) and obesity tends to be less prevalent (P = 0.07). Importantly, the G allele is associated with a lower prevalence of metabolic syndrome (P = 0.02). After adjusting for BMI, the above associations were attenuated. Independently of age, sex, and BMI, the minor allele is also associated with lower systolic blood pressure (-6.0 mmHg [2.5], P = 0.02) and lower prevalence of hypertension (odds ratio 0.41 [95% CI 0.20-0.83], P = 0.01).

CONCLUSIONS

The association between the minor allele of rs5068 and a favorable cardiometabolic phenotype that we previously reported in a U.S. population is now replicated in a Mediterranean population in which the G allele of rs5068 is associated with lower blood pressure, BMI, and prevalence of hypertension and metabolic syndrome. These findings may lead to a diagnostic strategy to assess cardiometabolic risk and lay the foundation for the future development of an ANP or ANP-like therapy for metabolic syndrome.

A novel APOB mutation identified by exome sequencing cosegregates with steatosis, liver cancer, and hypocholesterolemia

OBJECTIVE

In familial hypobetalipoproteinemia, fatty liver is a characteristic feature, and there are several reports of associated cirrhosis and hepatocarcinoma. We investigated a large kindred in which low-density lipoprotein cholesterol, fatty liver, and hepatocarcinoma displayed an autosomal dominant pattern of inheritance.

APPROACH AND RESULTS

The proband was a 25-year-old female with low plasma cholesterol and hepatic steatosis. Low plasma levels of total cholesterol and fatty liver were observed in 10 more family members; 1 member was affected by liver cirrhosis, and 4 more subjects died of either hepatocarcinoma or carcinoma on cirrhosis. To identify the causal mutation in this family, we performed exome sequencing in 2 participants with hypocholesterolemia and fatty liver. Approximately 22 400 single nucleotide variants were identified in each sample. After variant filtering, 300 novel shared variants remained. A nonsense variant, p.K2240X, attributable to an A>T mutation in exon 26 of APOB (c.6718A>T) was identified, and this variant was confirmed by Sanger sequencing. The gentotypic analysis of 16 family members in total showed that this mutation segregated with the low cholesterol trait. In addition, genotyping of the PNPLA3 p.I148M did not show significant frequency differences between carriers and noncarriers of the c.6718A>T APOB gene mutation.

CONCLUSIONS

We used exome sequencing to discover a novel nonsense mutation in exon 26 of APOB (p.K2240X) responsible for low cholesterol and fatty liver in a large kindred. This mutation may also be responsible for cirrhosis and liver cancer in this family.

Abstract 423: A Combination of Metformin, Quercetin, and Curcumin Restores HDL Function and Improves Atherosclerosis Burden in LDLr-/-/ob.ob leptin-/- and LDLr-/- Mice by attenuating Insulin Resistance, Hyperglycemia, and Low-grade Inflammation

Cardiovascular disease risk in diabetics is 2-4 fold greater compared to non-diabetics. While dyslipidemia poorly explains excess risk in diabetics, glucose intolerance leads to increased macrophage infiltration, arterial stiffness, and modifies vascular tone. Enhanced lipid peroxidation in diabetes mellitus contributes to increased formation of free radicals, leading to accelerated glycation and oxidative stress, which causes HDL modification. The objective of the present study was to: a) investigate HDL function and atherosclerosis burden in animal model of diabetes, hyperlipidemia, and low-grade inflammation; and b) evaluate regression of preformed lesions following treatment with a proprietary formulation (COMB) of metformin (MET) with anti-oxidant and anti-inflammatory agents, quercetin and curcumin. We used LDLr-/-/leptin-/-ob/ob (DKO) and LDLr-/- (SKO) mice fed Western Diet for 10 weeks to develop lesion formation followed by treatment with MET (150 mpk) or COMB for 6 weeks (bid). Lipid profile, lesion formation, and OGTT were measured. We also measured HDL functionality by ABCA1-dependent cholesterol efflux in the serum, and in a separate cohort, cholesterol efflux using 3H-cholesterol-loaded J774 cells. Atherosclerotic lesion formation in DKO was greater (27%) compared to SKO. Impaired glucose tolerance, insulin resistance, and proinflammatory index was found to be associated with HDL functionality and atherosclerosis burden. Treatment with COMB attenuated hyperglycemia, insulin resistance and inflammation, and restored HDL function and promoted lesion regression (-24% in DKO, and -15% in SKO). COMB showed greater efficacy compared to MET, demonstrating the benefit of controlling glycemia and inflammation to restore HDL function and enhance lesion regression. Preliminary results in diabetics (n=10) and age and sex matched non-diabetic individuals (n=10) showed impairment in ABCA1-mediated cholesterol efflux in the serum of diabetics (-18% vs control). In summary, these data suggest that HDL dysfunction in diabetes mellitus is one of the risk factors of atherosclerotic lesion formation, and attenuation of hyperglycemia, oxidative stress, and inflammation may improve HDL function and promote lesion regression.

Nonalcoholic fatty liver and metabolic syndrome in Italy: results from a multicentric study of the Italian Arteriosclerosis society

Nonalcoholic fatty liver disease (NAFLD) is associated with all the components of metabolic syndrome (MS) and might to be considered an additional component of MS itself. The Italian Society for the Study of Atherosclerosis (SISA) in 2005 started a research project aimed to study the NAFLD, using ultrasound (US), in nondiabetic MS subjects matching at least one of the ATP III criteria for HDL-C or triglycerides [TG]. Prevalence of US-NAFLD and its associated risk factors and prevalence of hypertransaminasemia and its possible determinants were evaluated. NAFLD prevalence was 0.78. Men with steatosis compared to men without steatosis were younger (P < 0.05) with higher TG (P < 0.03), homeostasis model assessment insulin resistance (HOMA-R) (P < 0.003), and visceral fat thickness (VFT) (P < 0.0001). Women with steatosis showed higher TG (P < 0.05), HOMA-R (P < 0.04), VFT (P < 0.0001), and lower age (P < 0.05). At multivariate analyses, VFT (P < 0.0001), HOMA-R (P < 0.02), and TG/HDL (P < 0.05) were associated with severity of NAFLD. Age (P < 0.05), LogTG (P < 0.005), and VFT (P < 0.01) were associated with higher ALT. The US prevalence of steatosis in this study (0.78) is the highest reported in patients with MS. Considering the exclusion of severe obese and diabetic patients and the recruitment criteria, this finding highlights the prominent role played by the alterations of lipid metabolism in the pathogenesis of NAFLD.

Efficacy and safety of a microsomal triglyceride transfer protein inhibitor in patients with homozygous familial hypercholesterolaemia: a single-arm, open-label, phase 3 study

BACKGROUND

Patients with homozygous familial hypercholesterolaemia respond inadequately to existing drugs. We aimed to assess the efficacy and safety of the microsomal triglyceride transfer protein inhibitor lomitapide in adults with this disease.

METHODS

We did a single-arm, open-label, phase 3 study of lomitapide for treatment of patients with homozygous familial hypercholesterolemia. Current lipid lowering therapy was maintained from 6 weeks before baseline through to at least week 26. Lomitapide dose was escalated on the basis of safety and tolerability from 5 mg to a maximum of 60 mg a day. The primary endpoint was mean percent change in levels of LDL cholesterol from baseline to week 26, after which patients remained on lomitapide through to week 78 for safety assessment. Percent change from baseline to week 26 was assessed with a mixed linear model.

FINDINGS

29 men and women with homozygous familial hypercholesterolaemia, aged 18 years or older, were recruited from 11 centres in four countries (USA, Canada, South Africa, and Italy). 23 of 29 enrolled patients completed both the efficacy phase (26 weeks) and the full study (78 weeks). The median dose of lomitapide was 40 mg a day. LDL cholesterol was reduced by 50% (95% CI -62 to -39) from baseline (mean 8·7 mmol/L [SD 2·9]) to week 26 (4·3 mmol/L [2·5]; p<0·0001). Levels of LDL cholesterol were lower than 2·6 mmol/L in eight patients at 26 weeks. Concentrations of LDL cholesterol remained reduced by 44% (95% CI -57 to -31; p<0·0001) at week 56 and 38% (-52 to -24; p<0·0001) at week 78. Gastrointestinal symptoms were the most common adverse event. Four patients had aminotransaminase levels of more than five times the upper limit of normal, which resolved after dose reduction or temporary interruption of lomitapide. No patient permanently discontinued treatment because of liver abnormalities.

INTERPRETATION

Our study suggests that treatment with lomitapide could be a valuable drug in the management of homozygous familial hypercholesterolaemia.

FUNDING

FDA Office of the Orphan Product Development, Aegerion Pharmaceuticals.

Protein oxidation in a group of subjects with metabolic syndrome

AIMS

To examine the protein oxidation, marker of the oxidative stress, in metabolic syndrome (MS).

METHODS

We enrolled 106 subjects (45 women and 61 men) with MS of which 43 (14 women and 27 men) were with diabetes mellitus and 63 (31 women and 32 men) were without diabetes mellitus, and 54 subjects (19 women and 35 men) as control group. The protein oxidation, expressed as carbonyl groups, was measured by an enzyme-like immunosorbent assay (ELISA) kit (BioCell PC test kit, Enzo Life Sciences AG, Switzerland).

RESULTS

In the whole group of MS subjects, in comparison with control group, a significant increase in carbonyl groups was present. The same datum was also evident between control group and diabetic subjects with MS and between control group and nondiabetic subjects with MS. No difference was observed between the two subgroups (diabetic and nondiabetic subjects with MS) about NOx. Few information were obtained examining the linear regression among carbonyl groups, age, BMI, waist circumference, blood pressure values and metabolic pattern of MS subjects.

CONCLUSIONS

In MS subject we observed an increase of protein oxidation not influenced by diabetes mellitus. Several strategies may be employed to reduce this parameter.

Prothrombotic gene variants as risk factors of acute myocardial infarction in young women

Background

Acute myocardial infarction (AMI) in young women represent an extreme phenotype associated with a higher mortality compared with similarly aged men. Prothrombotic gene variants could play a role as risk factors for AMI at young age.

Methods

We studied Factor V Leiden, FII G20210A, MTHFR C677T and beta-fibrinogen -455G>A variants by real-time PCR in 955 young AMI (362 females) and in 698 AMI (245 females) patients. The data were compared to those obtained in 909 unrelated subjects (458 females) from the general population of the same geographical area (southern Italy).

Results

In young AMI females, the allelic frequency of either FV Leiden and of FII G20210A was significantly higher versus the general population (O.R.: 3.67 for FV Leiden and O.R.: 3.84 for FII G20210A; p<0.001). Among AMI patients we showed only in males that the allelic frequency of the MTHFR C677T variant was significantly higher as compared to the general population. Such difference was due to a significantly higher frequency in AMI males of the MTHFR C677T variant homozygous genotype (O.R. 3.05).

Discussion and conclusion

Our data confirm that young AMI in females is a peculiar phenotype with specific risk factors as the increased plasma procoagulant activity of FV and FII. On the contrary, the homozygous state for the 677T MTHFR variant may cause increased levels of homocysteine and/or an altered folate status and thus an increased risk for AMI, particularly in males. The knowledge of such risk factors (that may be easily identified by molecular analysis) may help to improve prevention strategies for acute coronary diseases in specific risk-group subjects.

Evaluation of nitric oxide metabolites in a group of subjects with metabolic syndrome

AIM

To evaluate the concentration of metabolites (NO(2)(-), NO(3)(-)) of nitric oxide (NO) in metabolic syndrome (MS).

MATERIALS AND METHODS

We enrolled 106 subjects (45 women and 61 men) with MS of which 43 (14 women and 27 men) with diabetes mellitus and 63 (31 women and 32 men) without diabetes mellitus, and 54 subjects (19 women and 35 men) as control group. The nitric oxide metabolites (nitrite+nitrate=NOx) were evaluated employing the Griess reagent.

RESULTS

In the whole group of MS subjects was evident, in comparison with control group, a significant increase in NOx. The same finding was also present between control group and diabetic subjects with MS and between control group and nondiabetic subjects with MS. No difference was observed between the two subgroups (diabetic and nondiabetic subjects with MS) about NOx. Contrasting information were obtained examining the linear regression among NOx, age, anthropometric profile, blood pressure values and glycometabolic pattern of subjects with MS.

CONCLUSIONS

In MS subjects we found a significant increase in NOx not influenced by diabetes mellitus. The NOx is a parameter that must be considered in MS keeping in mind that its behavior is related to chronic inflammation that accompanies this clinical condition.

Prediction of incident type 2 diabetes mellitus based on a twenty-year follow-up of the Ventimiglia heart study

A novel algorithm to predict incident type 2 diabetes mellitus (iT2DM) is presented considering data from a 20-year prospective study in a Southern Italy population. Eight hundred and fifty-eight out of 1,351 subjects (24-85 years range of age) were selected. Incident type 2 diabetes was diagnosed in 103 patients in a 20-year follow-up. The Finnish Diabetes Risk Score (FINDRISC) and the Framingham Offspring Study simple clinical model (FOS) have been used as reference algorithms. Two custom algorithms have been created using Cox parametric hazard models followed by PROBIT analyses: the first one (VHSRISK) includes all the study subjects and the second one (VHS95RISK) evaluates separately subjects with baseline fasting blood glucose (FBG) above/below 5.2 mmol/L (95 mg/dL). The 44 iT2DM cases below 5.2 mmol/L of baseline FBG were predicted by high LDL cholesterol, metabolic syndrome (ATPIII criteria), BMI > 30 kg/m(2), and high factor VII activity. The 59 cases above the FBG threshold were predicted by FBG classes, hypertension, and age. ROC areas for iT2DM prediction were: FINDRISC = 0.759, FOS = 0.762, VHSRISK = 0.789, and VHS95RISK = 0.803. In a Mediterranean population, the use of a custom generated algorithm evaluating separately low/high FBG subjects improves the prediction of iT2DM in subjects classified at lower risk by common estimation algorithms.

Identification of a novel mutation of MTP gene in a patient with abetalipoproteinemia

Abetalipoproteinemia (ABL), or Bassen-Kornzweig syndrome, is a rare autosomal recessive disorder of lipoprotein metabolism, characterized by fat malabsorption, hypocholesterolemia retinitis pigmentosa, progressive neuropathy and acanthocytosis from early infancy. We describe the clinical and molecular characterization of a 6-month-old infant born of consanguineous, apparently healthy parents from Iran. The patient was hospitalized because of failure to thrive, greasy stool and vomiting. The patient's serum lipid profile, the clinical phenotype and the duodenal histology suggested the clinical diagnosis of ABL. The MTP gene analysis by direct sequencing revealed a novel homozygous mutation (c.1586 A > G-H529R). The parents were heterozygotes for the same mutation and interestingly the father showed a lipid profile characterized by a slight reduction of total and LDL-cholesterol plasma levels.

Lipase maturation factor 1 is required for endothelial lipase activity

Lipase maturation factor 1 (Lmf1) is an endoplasmic reticulum (ER) membrane protein involved in the posttranslational folding and/or assembly of lipoprotein lipase (LPL) and hepatic lipase (HL) into active enzymes. Mutations in Lmf1 are associated with diminished LPL and HL activities ("combined lipase deficiency") and result in severe hypertriglyceridemia in mice as well as in human subjects. Here, we investigate whether endothelial lipase (EL) also requires Lmf1 to attain enzymatic activity. We demonstrate that cells harboring a (cld) loss-of-function mutation in the Lmf1 gene are unable to generate active EL, but they regain this capacity after reconstitution with the Lmf1 wild type. Furthermore, we show that cellular EL copurifies with Lmf1, indicating their physical interaction in the ER. Finally, we determined that post-heparin phospholipase activity in a patient with the LMF1(W464X) mutation is reduced by more than 95% compared with that in controls. Thus, our study indicates that EL is critically dependent on Lmf1 for its maturation in the ER and demonstrates that Lmf1 is a required factor for all three vascular lipases, LPL, HL, and EL.

Plasma non-cholesterol sterols in primary hypobetalipoproteinemia

Primary hypobetalipoproteinemia (pHBL) is characterized by plasma cholesterol levels <5th percentile of a population distribution. Plasma non-cholesterol sterols (NCS) are markers of cholesterol liver synthesis and intestinal absorption. Plasma NCS were measured in 111 pHBL subjects, 108 low cholesterol (LC) and 253 normal cholesterol (NC) controls to gain information on cholesterol metabolism in pHBL, and to assess whether NCS measurements may aid in distinguishing pHBL from LC controls. pHBL subjects compared with LC controls were characterized by increased cholesterol absorption (campesterol/TC) while the synthesis (lathosterol/TC) was not increased. The analysis of pHBL subjects divided by gene defect showed a high campesterol/TC ratio in familial HBL (FHBL) carriers of apolipoproteinB (ApoB) truncations longer than ApoB48 and in FHBL without known gene defect ("not linked"). One not linked kindred was characterized by an increase of the 7-dehydrocholesterol/latho ratio. In a discriminant analysis plasma NCS did not improve the power of TC levels to distinguish FHBL from LC controls. In conclusion, increased cholesterol absorption was found in FHBL subjects harbouring truncations of ApoB>ApoB48, and FHBL harbouring as yet unknown molecular defects. Not linked FHBL kindred are not homogeneous in terms of plasma NCS levels. NCS cannot replace genetic HBL analysis.

Modification of the lipidic and coagulative pattern in postmenopause women: effect of hormone replacement therapy

AIM

We evaluated the changes of lipidic and coagulative pattern during menopause and the influence of hormone replacement therapy (HRT) on these parameters.

METHODS

We considered 158 patients divided into 2 groups: Group I consisted of 127 women in physiological/surgical menopause and Group II of 31 women with childbearing potential. Subsequently, we considered a group III formed of 34 patients from menopausal women (group I) who underwent three months of HRT. We evaluated total-cholesterol (TC), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), triglycerides (TG), lipoprotein (a) (Lpa), fibrinogen, antithrombin III (ATIII), factor VII (FVII) and tissue factor pathway inhibitor (TFPI).

RESULTS

We found a worse lipid profile in the post-menopausal group compared to controls (TC 243.8+/-29.7 vs 217.9+/-32.7 mg%, P=0.002; TG 121.5+/-68.4 vs 88.6+/-53.0 mg%, P=0.039; LDL-C 163.0+/-27.9 vs 136.2+/-29.6 mg%, P=0.004; HDL-C 60.9+/-14.9 vs 64.1+/-14.6 mg%, P=ns). With regard to the coagulative pattern, fibrinogen was significantly higher in the post-menopausal group (fibrinogen: 273.3+/-67.4 vs 243.8+/-39.5 mg%, P=0.013; ATIII 112.2+/-11.7 vs 117.5+/-12.7% %, P=0.059; FVII 121.6+/-11.3 vs 117.6+/-10.8 mg%, P=ns; TFPI activity 2.5+/-2.3 vs 2.1+/-1.1 U/mL, P=ns; TFPI antigen 120+/-38 vs 127+/-39 U/mL, P=ns). Comparing the same parameters, before and after three months of HRT, in patients of Group III we observed a significant improvement of TC and TG levels (TC from 232.3+/-42.7 to 215.2+/-37.6 mg%, P=0.0001; TG from 103.7+/-56.8 to 95.0+/-44.3 mg%, P=0.059; HDL-C from 62.3+/-12.9 to 63.6+/-12.6 mg%, P=ns; LDL-C from 149.3+/-38.7 to 132.6+/-34.5 mg%, P=0.0001). The following changes were observed with regard to coagulative parameters: fibrinogen from 270.9+/-69.4 to 253.2+/-56.2 mg%, P=0.07; ATIII from 113.5+/-11.4 to 110.8+/-13.2 mg%, P=0.198; FVII from 108.6+/-18.0 to 104.4+/-17.5 mg%, 0.014. TFPI activity from 2.6+/-2.3 to 2.3+/-1.4 U/ml, P=ns; TFPI antigen from 68+/-13 to 87+/-22 U/mL, P=0.001.

CONCLUSION

Our data confirm the presence of an alteration in lipidic and coagulative pattern in post menopausal women and positive changes after HRT.

Variable phenotypic expression of chylomicron retention disease in a kindred carrying a mutation of the Sara2 gene

Chylomicron retention disease is a recessive inherited disorder characterized by fat malabsorption and steatorrhea and is associated with failure to thrive in infancy. We describe a kindred carrying a mutation of Sara2 gene causing a chylomicron retention phenotype. The proband was a 5-month-old baby, born of consanguineous, apparently healthy parents from Morocco, with failure to thrive. There was a large quantity of fats in feces and malabsorption of fat-soluble vitamins. Intestinal biopsies showed a diffused enterocyte vacuolization with large cytosolic lipid droplets. Chylomicron retention disease or Anderson disease was hypothesized, and the Sara2 gene was analyzed by direct sequencing. Analysis of the Sara2 gene in the proband identified a 2-nucleotide homozygous deletion in exon 3 leading to a premature stop codon (c.75-76 del TG-L28fsX34). The father was heterozygous for the same mutation, whereas the proband's mother was homozygous, suggesting a variable phenotypic expression of the molecular defect. More studies are needed to understand the reasons of the phenotypic variability of the same molecular defect in the same family.

A novel component of the metabolic syndrome: the oxidative stress

The metabolic syndrome (MS) represents a cluster of cardiovascular (CV) risk factors associated to CV disease and type 2 diabetes. It is still under debate whether MS is a mere aggregation of risk factors or it represents a clinical entity with visceral obesity as underlying pathophysiological trigger. The publication of several diagnostic criteria of MS by scientific associations or experts panels reflects this uncertainty in understanding the real nature of MS. Besides the metabolic disturbances of MS, as visceral obesity, hypertriglyceridemia, low HDL cholesterol, hypertension and hyperglycemia, novel mechanisms of arterial damage have been identified. This paper reviews the evidence showing that MS and MS factors are characterized by increased oxidative stress, a relevant factor contributing to the development of metabolic and cardiovascular complications. In the next future, the measure of plasma oxidative stress may contribute to identify a subset of MS patients at increased CV risk, candidates to more intensive therapies.

Novel LMF1 nonsense mutation in a patient with severe hypertriglyceridemia

CONTEXT

Lipase maturation factor 1 (LMF1) gene is a novel candidate gene in severe hypertriglyceridemia. Lmf1 is involved in the maturation of lipoprotein lipase (LPL) and hepatic lipase in endoplasmic reticulum. To date only one patient with severe hypertriglyceridemia and related disorders was found to be homozygous for a nonsense mutation in LMF1 gene (Y439X).

OBJECTIVE

The objective of the study was to investigate LMF1 gene in hypertriglyceridemic patients in whom mutations in LPL, APOC2, and APOA5 genes had been excluded.

RESULTS

The resequencing of LMF1 gene led to the discovery of a novel homozygous nonsense mutation in one patient with severe hypertriglyceridemia and recurrent episodes of pancreatitis. The mutation causes a G>A substitution in exon 9 (c.1395G>A), leading to a premature stop codon (W464X). LPL activity and mass were reduced by 76 and 50%, respectively, compared with normolipidemic controls. The proband over the years has shown a good response to treatment. The proband's son, heterozygous for the W464X, shows normal plasma triglyceride levels.

CONCLUSIONS

We identified the second novel pathogenic mutation in LMF1 gene in a patient with severe hypertriglyceridemia. LPL deficiency in our patient was milder than in the carrier of the Y439X previously described.