The burden of familial chylomicronemia syndrome in Canadian patients

Clinical characterization and mutation spectrum of patients with hypertriglyceridemia in a German outpatient clinic

BACKGROUND

Severe hypertriglyceridemia (HTG) has predominantly multifactorial causes (MCS). Yet a small subset of patients have the monogenetic form (FCS). It remains a challenge to distinguish patients clinically, since decompensated MCS might mimic FCS´s severity. Aim of the current study was to determine clinical criteria that could sufficiently distinguish both forms as well as to apply the FCS score proposed by Moulin and colleagues.

METHODS

We retrospectively studied 72 patients who presented with severe HTG in our clinic during a time span of seven years and received genetic testing. We classified genetic variants (ACMG-criteria), followed by genetic categorization into MCS or FCS. Clinical data were gathered from the medical records and the FCS score was calculated for each patient.

RESULTS

Molecular genetic screening revealed eight FCS patients and 64 MCS patients. Altogether, we found 13 pathogenic variants of which four have not been described before. The FCS patients showed a significantly higher median triglyceride level compared to the MCS. The FCS score yielded a sensitivity of 75% and a specificity of 93.7% in our cohort, and significantly differentiated between the FCS and MCS group (p<0.001).

CONCLUSIONS

In our cohort we identified several variables that significantly differentiated FCS from MCS. The FCS score performed similar to the original study by Moulin, thereby further validating the discriminatory power of the FCS score in an independent cohort.

Validation of the familial chylomicronaemia syndrome (FCS) score in an ethnically diverse cohort from UK FCS registry: Implications for diagnosis and differentiation from multifactorial chylomicronaemia syndrome (MCS)

BACKGROUND AND AIMS

Prognosis and management differ between familial chylomicronaemia syndrome (FCS), a rare autosomal recessive disorder, and multifactorial chylomicronaemia syndrome (MCS) or severe mixed hyperlipidaemia. A clinical scoring tool to differentiate these conditions has been devised but not been validated in other populations. The objective of this study was to validate this score in the UK population and identify any additional factors that might improve it.

METHODS

A retrospective validation study was conducted using data from 151 patients comprising 75 FCS and 76 MCS patients. All participants had undergone genetic testing for genes implicated in FCS. Validation was performed by standard methods. Additional variables were identified from clinical data by logistic regression analysis.

RESULTS

At the recommended FCS score threshold ≥10 points, the sensitivity and specificity of the score in the UK population were 96% and 75%, respectively. The receiver operating characteristic (ROC) curve analysis yielded an area under the curve (AUC) of 0.88 (95% CI 0.83-0.94, p < 0.001). This study identified non-European (predominantly South Asian) ethnicity, parental consanguinity, body mass index (BMI) < 25 kg/m2, and recurrent pancreatitis as additional positive predictors, while BMI >30 kg/m2 was found to be a negative predictor for FCS. However, inclusion of additional FCS predictors had no significant impact on performance of standard FCS score.

CONCLUSIONS

Our study validates the FCS score in the UK population to distinguish FCS from MCS. While additional FCS predictors were identified, they did not improve further the score diagnostic performance.

Executive summary of the Hellenic Atherosclerosis Society guidelines for the diagnosis and treatment of dyslipidemias - 2023

Atherosclerotic cardiovascular disease (ASCVD) remains the main cause of death worldwide, and thus its prevention, early diagnosis and treatment is of paramount importance. Dyslipidemia represents a major ASCVD risk factor that should be adequately managed at different clinical settings. 2023 guidelines of the Hellenic Atherosclerosis Society focus on the assessment of ASCVD risk, laboratory evaluation of dyslipidemias, new and emerging lipid-lowering drugs, as well as diagnosis and treatment of lipid disorders in women, the elderly and in patients with familial hypercholesterolemia, acute coronary syndromes, heart failure, stroke, chronic kidney disease, diabetes, autoimmune diseases, and non-alcoholic fatty liver disease. Statin intolerance is also discussed.

Long-Term Nutritional Counseling for a Patient with Lipoprotein Lipase Deficiency

A one-year-and-nine-month-old Japanese boy was admitted with hypertriglyceridemia (fasting triglycerides 2548 mg/dL). After close examination, he was diagnosed with lipoprotein lipase (LPL) deficiency (compound heterozygous) and was immediately started on a fat-restricted dietary therapy. He responded well to the regimen (1200 kcal/day, 20 g fat/day) and his triglycerides decreased to 628 mg/dL within 7 days of starting the dietary therapy. It was decided to manage his illness without using any drugs because he was still an infant and responded well to a fat-restricted diet. During his hospital stay, dietitians provided him with nutritional counseling using a food exchange list, which was designed to easily calculate the fat content by including foods that are commonly served. His family quickly learned the skills to prepare a fat-restricted diet. Moreover, since dietary restrictions may have impaired the child's growth and development, the dietitians continued to intervene regularly after the child was discharged from the hospital. The dietitians confirmed that the patient was receiving nutritional intake appropriate for his growth and discussed the dietary concerns in his daily life and how to participate in school events that involved eating and drinking. Nutritional counseling was provided every 3-4 months from disease onset to age 23 years, except for a 14-month break at age 20 years. The patient grew up without developing acute pancreatitis, a serious complication of LPL deficiency. The long-term intervention of dieticians is necessary to achieve a balance between living on a strict diet for disease management and ensuring appropriate nutritional intakes for growth/development.

Work participation in adults with rare genetic diseases - a scoping review

BACKGROUND

Work participation is a crucial aspect of health outcome and an important part of life for most people with rare genetic diseases. Despite that work participation is a social determinant of health and seems necessary for understanding health behaviours and quality of life, it is an under-researched and under-recognized aspect in many rare diseases. The objectives of this study was to map and describe existing research on work participation, identify research gaps, and point to research agendas in a selection of rare genetic diseases.

METHODS

A scoping review was performed by searching relevant literature in bibliographic databases and other sources. Studies addressing work participation in people with rare genetic diseases published in peer reviewed journals were assessed using EndNote and Rayyan. Data were mapped and extracted based on the research questions concerning the characteristics of the research.

RESULTS

Of 19,867 search results, 571 articles were read in full text, and 141 satisfied the eligibility criteria covering 33 different rare genetic diseases; 7 were reviews and 134 primary research articles. In 21% of the articles the primary aim was to investigate work participation. The extent of studies varied between the different diseases. Two diseases had more than 20 articles, but most had only one or two articles. Cross-sectional quantitative studies were predominant, with few utilizing prospective or qualitative design. Nearly all articles (96%) reported information about work participation rate, and 45% also included information about factors associated with work participation and work disability. Due to differences in methodologies, cultures and respondents, comparison between and within diseases are difficult. Nevertheless, studies indicated that many people with different rare genetic diseases experience challenges related to work, closely associated to the symptoms of the disease.

CONCLUSION

While studies indicate high prevalence of work disability in many patients with rare diseases, the research is scarce and fragmented. More research is warranted. Information about the unique challenges of living with different rare diseases is crucial for health and welfare systems to better facilitate work participation. In addition, the changing nature of work in the digital age, may also open up new possibilities for people with rare genetic diseases and should be explored.

Correlation between chylomicronemia diagnosis scores and post-heparin lipoprotein lipase activity

INTRODUCTION

Sustained chylomicronemia is a defect in post-prandial triglyceride management characterized by severe hypertriglyceridemia (triglyceride > 10 mmol/L) due to functional or genetic defects in lipoprotein lipase (LPL)-mediated triglyceride-rich lipoprotein lipolysis. Familial chylomicronemia syndrome (FCS) is a rare mendelian form of chylomicronemia caused by loss-of-function variants in LPL or LPL-related genes. Most individuals with chylomicronemia however present multifactorial chylomicronemia (MCS), in which LPL bio-availability and activity are variable. FCS and MCS differ in terms of clinical characteristics and risk of disease, and diagnosis scoring systems have been proposed to accurately distinguish FCS from MCS.

OBJECTIVE

The aim of this study was to assess the strength of the relationship between plasma post-heparin LPL activity and two published chylomicronemia diagnosis scoring systems.

DESIGN AND METHODS

Post-heparin plasma LPL activity was measured using colorimetric assays in a sample of 29 subjects with sustained chylomicronemia (20 FCS and 9 MCS). Chylomicronemia diagnosis scores were obtained for all subjects using the scoring system A (model A), which integrates apolipoprotein B and free glycerol, a surrogate marker of triglyceride hydrolysis, and the scoring system B (model B). Correlation analyses were conducted to estimate the linear relationship between LPL activity and the two diagnosis scoring systems.

RESULTS

There was a significant (p < 0.001) difference in post-heparin LPL activity between FCS and MCS. Both scoring systems significantly correlated with post-heparin LPL activity (model A: r_s = -0.64, p < 0.001; model B: r_s = -0.54, p = 0.002).

CONCLUSIONS

These result suggest that chylomicronemia diagnosis scoring systems correlate with LPL activity and adequately contribute to distinguish FCS from MCS.

Analyses of familial chylomicronemia syndrome in Pereira, Colombia 2010-2020: a cross-sectional study

BACKGROUND AND AIM

Familial chylomicronemia syndrome (FCS) is a rare autosomal recessive metabolic disorder caused by mutations in genes involved in chylomicron metabolism. On the other hand, multifactorial chylomicronemia syndrome (MCS) is a polygenic disorder and the most frequent cause of chylomicronemia, which results from the presence of multiple genetic variants related to chylomicron metabolism, in addition to secondary factors. Indeed, the genetic determinants that predispose to MCS are the presence of a heterozygous rare variant or an accumulation of several SNPs (oligo/polygenic). However, their clinical, paraclinical, and molecular features are not well established in our country. The objective of this study was to describe the development and results of a screening program for severe hypertriglyceridemia in Colombia.

METHODS

A cross-sectional study was performed. All patients aged >18 years with triglyceride levels ≥500 mg/dL from 2010 to 2020 were included. The program was developed in three stages: 1. Review of electronic records and identification of suspected cases based on laboratory findings (triglyceride levels ≥500 mg/dL); 2. Identification of suspected cases based on laboratory findings that also allowed us to exclude secondary factors; 3. Patients with FCS scores <8 were excluded. The remaining patients underwent molecular analysis.

RESULTS

In total, we categorized 2415 patients as suspected clinical cases with a mean age of 53 years, of which 68% corresponded to male patients. The mean triglyceride levels were 705.37 mg/dL (standard deviation [SD] 335.9 mg/dL). After applying the FCS score, 2.4% (n = 18) of patients met the probable case definition and underwent a molecular test. Additionally, 7 patients had unique variants in the APOA5 gene (c.694 T > C; p. Ser232Pro) or in the GPIHBP1 gene (c.523G > C; p. Gly175Arg), for an apparent prevalence of familial chylomicronemia in the consulting population of 0.41 per 1.000 patients with severe HTG measurement. No previously reported pathogenic variants were detected.

CONCLUSION

This study describes a screening program for the detection of severe hypertriglyceridemia. Although we identified seven patients as carriers of a variant in the APOA5 gene, we diagnosed only one patient with FCS. We believe that more programs of these characteristics should be developed in our region, given the importance of early detection of this metabolic disorder.

Qualitative development of the PROMIS Profile v1.0-Familial Chylomicronemia Syndrome (FCS) 28

PURPOSE

Familial chylomicronemia syndrome (FCS) is a rare genetic disorder characterized by high triglyceride levels, significant disease burden, and negative impacts on health-related quality of life. This project aimed to create a PROMIS-based patient-reported outcome measure that represents valid and important concerns for patients with FCS.

METHODS

We reviewed the literature and data from a previous qualitative study of FCS to identify key FCS symptoms and impacts, which were mapped to PROMIS domains to create a pool of eligible items. Candidate items were reduced per expert feedback and patients with FCS completed cognitive interviews to confirm content validity and measure content.

RESULTS

Literature and qualitative data review identified ten key symptoms and 12 key impacts of FCS, including abdominal pain, fatigue, difficulty thinking, and worry about pancreatitis attacks. We identified 96 items primarily from PROMIS, supplemented with items from the Quality of Life in Neurological Disorders™ (Neuro-QoL™) and the Functional Assessment of Chronic Illness Therapy (FACIT) measurement systems. This pool was reduced to 32 candidate items, which were assessed via cognitive interviews with eight participants with FCS. Cognitive interview results and additional expert feedback led to the removal of four items and finalization of the PROMIS Profile v1.0-familial chylomicronemia syndrome (FCS) 28.

CONCLUSIONS

The PROMIS Profile v1.0-familial chylomicronemia syndrome (FCS) 28 provides strong content validity for assessing quality of life among patients with FCS. The benefits of PROMIS, including norm-referenced mean values for each measure, will facilitate comparison of patients with FCS to other clinical populations.

Efficacy and safety of lomitapide in familial chylomicronaemia syndrome

BACKGROUND AND AIMS

Familial chylomicronaemia syndrome (FCS) is a rare autosomal recessive disorder, resulting in elevated triglycerides (TGs), abdominal pain and pancreatitis. Treatment options are limited. Lomitapide, a microsomal triglyceride transfer protein inhibitor, is approved for the treatment of homozygous familial hypercholesterolaemia. Whether its therapeutic use may be extended to FCS remains unknown. The aim of this study was to evaluate the efficacy and safety of lomitapide in adult patients with FCS.

METHODS

The open-label, single-arm 'LOCHNES' study of lomitapide in FCS enrolled patients >18 years with genetically confirmed FCS, elevated fasting TG ≥ 750 mg/dL and history of pancreatitis. Patients were administered lomitapide to the maximum tolerated dose for 26 weeks. The primary endpoint was the percent change in TGs from baseline to Week 26.

RESULTS

Eighteen patients were enrolled with median baseline TG levels 1803.5 mg/dL (97.5% CI, 1452-2391 mg/dL). At Week 26, median fasting TGs were reduced to 305 mg/dL (97.5% CI 219-801 mg/dL; 70.5% reduction); median lomitapide dose was 35 mg/day; 13 patients achieved TGs ≤750 mg/dL. Adverse events were mild to moderate and mainly related to gastrointestinal tolerability. Liver imaging at baseline and Week 26 revealed hepatic fat increases from median 12.0%-32.5%, while median hepatic stiffness remained normal. No patient experienced acute pancreatitis or severe abdominal pain during lomitapide treatment.

CONCLUSIONS

Lomitapide is effective and well tolerated in reducing TGs in FCS patients with a history of pancreatitis. Larger studies are warranted to determine lomitapide effectiveness in FCS.

New Therapies for Primary Hyperlipidemia

Primary hyperlipidemias include a heterogeneous set of monogenic and polygenic conditions characterized by a strong family aggregation, severe forms of hypercholesterolemia and/or hypertriglyceridemia, appearance early on life, and a high risk of cardiovascular events and/or recurrent pancreatitis. In real life, a small proportion of the primary hyperlipidemia cases is recognized and treated properly. Our goal is to present an update of current and upcoming therapies for patients with primary hyperlipidemia. Recently, new lipid-lowering medications have obtained authorization from the U.S. Food and Drug Administration and the European Medicines Agency. These drugs target metabolic pathways, including (adenosine 5'-triphosphates)-citrate lyase (bempedoic acid), proprotein convertase subtilisin/kexin 9 (inclisiran), apolipoprotein CIII (volanesorsen), and angiopoietin-like 3 (volanesorsen), that have additive effects with the actions of the currently available therapies (i.e., statins, ezetimibe or fibrates). We discuss the potential clinical indications for the novel medications. To conclude, the addition of these new medications to the therapeutic options for primary hyperlipidemia patients may increase the likelihood of achieving the treatment targets. Also, it could be a safer alternative for patients with side effects for the currently available drugs.

Rare Treatments for Rare Dyslipidemias: New Perspectives in the Treatment of Homozygous Familial Hypercholesterolemia (HoFH) and Familial Chylomicronemia Syndrome (FCS)

Purpose of Review

This review aims to summarize the most recent published literature concerning lomitapide and volanesorsen that are approved for the use in HoFH and FCS patients, respectively. Moreover, it will briefly revise the published evidence on novel, non-approved treatments that are under evaluation for the management of these rare forms of dyslipidemias

Recent Findings

The definition of rare dyslipidemias identifies a large number of severe disorders of lipid metabolism of genetic origin. Among them were homozygous familial hypercholesterolemia (HoFH) (OMIM #143890) and familial chylomicronemia syndrome (FCS) (OMIM #238600), which are characterized by a markedly impaired cholesterol- and triglyceride-containing lipoproteins metabolism. They are being particularly associated with poor health outcomes and quality of life. Considering the severity of these diseases, common lipid-lowering drugs are often ineffective or do not allow to achieve the recommended lipid targets to prevent the development of complications. Nowadays, several new drugs have been found to effectively treat HoFH and FCS with an acceptable safety profile.

Summary

Treating patients with HoFH and FCS remains very challenging. However, novel treatment options are emerging and might be considered in addition to conventional therapy for managing these diseases. These novel drugs will possibly change the natural history of these two rare and life-threatening diseases.

Hypertriglyceridemia: new approaches in management and treatment

PURPOSE OF REVIEW

Hypertriglyceridemia (HTG), a form of dyslipidemia characterized by elevated plasma of triglycerides (TG), is associated with an increased risk for acute pancreatitis. Moreover, HTG has recently been shown to be linked to the development of atherosclerotic cardiovascular disease (ASCVD); therefore, there is a great interest in better understanding the pathophysiology of HTG and improving its clinical management. In this review, we briefly describe TG metabolism, recent guidelines for the clinical management of HTG and provide an overview of the current and potential new therapies for HTG.

RECENT FINDINGS

Screening patients for HTG is valuable for not only identifying patients with extreme TG elevations, who are at risk for pancreatitis, but also for managing ASCVD risk in patients with more moderate forms of HTG. Therefore, the most recent USA guidelines for cardiovascular diseases recommend using TG as a risk enhancer test, leading to a more aggressive treatment of patients with intermediate risk. Currently, there are several available approaches for reducing plasma TG, which include lifestyle changes, fibrates and omega-3 fatty acid treatment. The addition of eicosapentaenoic acid (EPA) on top of statins has recently been shown to significantly reduce ASCVD events. Nevertheless, there is an unmet need for more effective treatment options. Several new therapies based on newly identified targets in TG metabolism, such as apolipoprotein C-III and angiopoietin-like 3 protein, are currently under development.

SUMMARY

The clinical management of HTG is important in the prevention and treatment of acute pancreatitis and also impacts on how ASCVD risk is managed. More work needs to be done to establish the mechanism for the ability of how EPA lowers ASCVD and how to best integrate it with other lipid-lowering therapies. The efficacy and safety of the novel therapies for HTG should be established soon in the ongoing late-stage clinical trials.