Considerations for Familial Chylomicronemia Diagnosis in the Era of Next-Generation Sequencing: A Latin American Perspective

Abstract Familial chylomicronemia syndrome (FCS) is an autosomal recessive disorder, characterized by alterations in the catabolism of chylomicrons and by increased levels of plasma triglycerides. It has been shown that about 60-90% of FCS patients have biallelic mutations in the LPL gene and the remaining patients have mutations in genes encoding proteins closely related to LPL function. The objective of this manuscript is to illustrate the different clinical scenarios of FCS presentation, and to guide practitioners on the usefulness of genetic tests in each of them. To this end, several published papers about recommendations for the diagnosis of FCS are discussed briefly, in addition to the presentation of several hypothetical cases, highlighting different clinical presentations and possible associated genetic findings. These cases illustrate the multiplicity of potential aspects of family history, clinical manifestations, biochemical parameters, and patterns of genetic variants found in genomic analyses of FCS.

Familial chylomicronemia syndrome: A comprehensive clinical and genetic approach

Abstract The familial chylomicronemia syndrome (FCS) is characterized by very high levels of circulating triglycerides. FCS is caused by lipoprotein lipase (LPL) deficiency resulting from homozygous or biallelic loss-of-function variants in the LPL or other related genes. Here, we report a case of severe hypertriglyceridemia refractory to conventional therapy in a male patient diagnosed at 33 years of age. LPL activity was below 20%. During the clinical course, the patient developed severe acute pancreatitis in addition to other complications. Two heterozygous variants (c.984G>A and c.1139+6T>C) which had not been previously reported in the major databases were identified in the LPL gene. Treatment with volanesorsen was proposed based on its approved indication as an adjunct to diet in adult patients with confirmed FCS and at high risk for pancreatitis. Volanesorsen was effective and well-tolerated, and the patient did not experience abdominal pain or any other manifestations. The assessment of genetic characterization is essential to guide treatment decisions during follow-up, in addition to the patient's history, their comorbidities and clinical stigmas.

Hipertrigliceridemia grave y síndrome de quilomicronemia familiar: una revisión de la literatura reciente / Severe hypertriglyceridemia and familial chylomicronemia syndrome: a review of recent literature

Resumen La hipertrigliceridemia (HTG) es un problema que se presenta con frecuencia en la práctica clínica. Su prevalencia en adultos es cercana al 10%. El espectro varía desde una predisposición que resulta en HTG solo en presencia de sobrepeso considerable o consumo excesivo de alcohol hasta mutaciones graves muy raras que pueden conducir a HTG grave en la infancia, incluso en ausencia de factores adicionales, como en el síndrome de quilomicronemia familiar (FCS, familial chylomicronemia syndrome). Este es un trastorno autosómico recesivo poco frecuente del metabolismo del quilomicrón que causa una importante elevación de los triglicéridos (>10 mmol/885 mg/dl). Esta condición está asociada con un riesgo significativo de pancreatitis aguda recurrente. La aproximación diagnóstica se logra mediante la caracterización fenotípica, y el hallazgo de la alteración genética ayuda a dar un diagnóstico más preciso. Además, se ha propuesto una puntuación clínica para el diagnóstico de FCS, pero necesita más validación. Las opciones de tratamiento disponibles para reducir los triglicéridos, como los fibratos y los ácidos grasos omega-3, no son eficaces en los pacientes con FCS. Actualmente, el único tratamiento sigue siendo una dieta de por vida muy baja en grasas, que reduce la formación de quilomicrones. Finalmente, los inhibidores de la apolipoproteína C-III están en desarrollo y podrían constituir opciones de tratamiento para estos pacientes. Considerando lo anterior, el objetivo de este artículo es realizar una revisión general sobre la HTG grave, con énfasis en el FCS, basados en la literatura disponible más reciente.

Abstract Hypertriglyceridemia (HTG) is a problem that occurs frequently in clinical practice. Its prevalence in adults is close to 10% and it varies between regions. The spectrum ranges from a disposition that results in HTG only in the presence of considerable overweight and/or excessive alcohol consumption to very rare serious mutations that can lead to severe HTG in childhood, even in the absence of additional factors such as familial chylomicronemia syndrome (FCS). This is a rare autosomal recessive disorder of chylomicron metabolism that causes a severe elevation in triglyceride levels (>10 mmol/885 mg/dL). This condition is associated with a significant risk of recurrent acute pancreatitis. Because this is a genetic condition, the optimal diagnostic strategy remains the genetic test. In addition, a clinical score for the diagnosis of FCS has been proposed but it needs further validation. Available treatment options to lower triglycerides, such as fibrates or omega-3 fatty acids, are not effective in patients with FCS. Currently, the cornerstone of treatment remains a very low-fat, lifetime diet that reduces chylomicron formation. Finally, apolipoprotein C-3 inhibitors are under development and may eventually be treatment options for these patients. The objective of this article is to carry out a general review of severe HTG, with an emphasis on FCS and based on the most recent available literature.

Familial chylomicronemia syndrome-induced acute necrotizing pancreatitis during pregnancy

Abstract Acute pancreatitis is a rare condition in pregnancy, associated with a high mortality rate. Hypertriglyceridemia represents its second most common cause.We present the case of a 38-year-old woman in the 24th week of gestation with a history of hypertriglyceridemia and recurrent episodes of pancreatitis. She was admitted to our hospital with acute pancreatitis due to severe hypertriglyceridemia. She was stabilized and treated with fibrates. Despite her favorable clinical course, she developed a second episode of acute pancreatitis complicated by multi-organ dysfunction and pancreatic necrosis, requiring a necrosectomy. The pregnancy was ended by cesarean section, after which three plasmapheresis sessions were performed. She is currently asymptomatic with stable triglyceride levels. Acute pancreatitis due to hypertriglyceridemia represents a diagnostic and therapeutic challenge in pregnant women, associated with serious maternal and fetal complications. When primary hypertriglyceridemia is suspected, such as familial chylomicronemia syndrome, the most important objective is preventing the onset of pancreatitis.

Quilomicronemia familiar / Familial chylomicronemia

Resumen La quilomicronemia familiar es una condición en que una mutación genética altera la capacidad de metabolizar los triglicéridos que viajan en las lipoproteínas, causando elevación extrema de triglicéridos plasmáticos y complicaciones asociadas. La complicación más frecuente es la pancreatitis, que puede llevar a falla multiorgánica o insuficiencia pancreática. La quilomicronemia familiar también afecta la calidad de vida, las relaciones sociales y el desarrollo profesional. El gen más frecuentemente afectado en la quilomicronemia familiar es el de lipoproteína lipasa-1 (LPL), enzima que hidroliza triglicéridos circulantes para su captación tisular. Mutaciones en genes (como APOC2, APOAV, LMF-1, GPIHBP-1) que codifican para proteínas que regulan la maduración, transporte o polimerización de lipoproteína lipasa-1, también pueden estar involucradas. Sin embargo, en cerca del 30% de los pacientes no se encuentra la variante causal. La quilomicronemia familiar debe sospecharse en casos de hipertrigliceridemia extrema, resistente al tratamiento convencional, o que se acompaña de xantomas eruptivos, lipemia retinalis o dolor abdominal. La disponibilidad de escalas de riesgo y pruebas genéticas deben promover la detección oportuna. La nutrición se basa en una dieta muy baja en grasa con adecuada suplencia de vitaminas liposolubles y ácidos grasos esenciales, además de evitar el consumo de alcohol. Si bien el tratamiento farmacológico incluye fibratos y ácidos grasos omega 3, el enfoque actual privilegia agentes biotecnológicos dirigidos a los defectos moleculares propios de la enfermedad. Ello incluye un oligonucleótido antisentido dirigido contra apoC-III (volanesorsen), un anticuerpo monoclonal contra la proteína similar a angiopoietina tipo 3 (evinacumab), y otros compuestos en desarrollo.

Abstract Familial chylomicronemia is a disease in which a genetic mutation affects the ability of the organism to metabolize triglycerides bound to lipoproteins, causing extremely high plasma triglycerides and associated consequences. The most frequent complication is acute pancreatitis, which may lead to multiorganic failure or pancreatic insufficiency. Familial chylomicronemia also exerts a profound negative impact on quality of life, social relationships and professional development. The gene most frequently affected is lipoprotein lipase-1 gene (LPL), the enzyme in charge of hydrolyzing circulating triglycerides for tissue uptake. Mutations in other genes regulating maturation, transport or polymerization (eg. APOC2, APOAV, LMF-1, GPIHBP-1) of lipoprotein lipase-1, may also be involved. However, in about 30% of patients the causal variant is not identified. Familial chylomicronemia should be suspected in patients with severe hypertriglyceridemia with poor response to conventional treatment, or accompanied by eruptive xanthomas, lipemia retinalis or abdominal pain. The availability of risk scores and genetic tests should facilitate its opportune detection and management. Nutritional therapy is based on a very-low-fat diet with adequate supply of lipid-soluble vitamins and essential fatty acids, plus avoidance of alcohol consumption. Current pharmacological treatment may include fibrates and omega-3 fatty acids but prioritizes biotechnological agents targeting the molecular disturbances of the disease. These include an antisense oligonucleotide against apoC-III (volanesorsen), a monoclonal antibody against angiopoietin-like protein-3 (evinacumab), and other agents currently in development.

A 1-month-old infant with chylomicronemia due to GPIHBP1 gene mutation treated by plasmapheresis

Chylomicronemia is a severe type of hypertriglyceridemia characterized by chylomicron accumulation that arises from a genetic defect in intravascular lipolysis. It requires urgent and proper management, because serious cases can be accompanied by pancreatic necrosis or persistent multiple organ failure. We present the case of a 1-month-old infant with chylomicronemia treated by plasmapheresis. His chylomicronemia was discovered incidentally when lactescent plasma was noticed during routine blood sampling during a hospital admission for fever and irritability. Laboratory investigation revealed marked triglyceridemia (>5,000 mg/dL) with high chylomicron levels. We therefore decided to perform a therapeutic plasmapheresis to prevent acute pancreatitis. Sequence analysis revealed a homozygous novel mutation in exon 4 of GPIHBP1: c.476delG (p.Gly159Alafs). Glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 (GPIHBP1) stabilizes the binding of chylomicrons near lipoprotein lipase and supports lipolysis. Mutations of GPIHBP1, the most recently discovered gene, can lead to severe hyperlipidemia and are known to make up only 2% of the monogenic mutations associated with chylomicronemia. The patient maintains mild hypertriglyceridemia without rebound after single plasmapheresis and maintenance fibrate medication so far. Here, we report an infant with chylomicronemia due to GPIHBP1 mutation, successfully treated by plasmapheresis.

Chylomicronemia Syndrome–A Rare Metabolic Disorder of Infancy

Chylomicronemia syndrome is a disorder passed down through families in which the body does not metabolize lipids. This causes fat particles called chylomicrons to build up in the blood. It is also known as Familial lipoprotein lipase (LpL) deficiency. Chylomicronemia syndrome occurs due to a rare genetic disorder in which the enzyme LpL is broken or missing and it causes accumulation of chylomicrons. This is known as Chylomicronemia. LpL is normally found in adipose tissue and muscle. It helps in the breakdown of lipids. Symptoms may start in infancy and include: Abdominal pain due to pancreatitis, neurological symptoms, xanthomas and failure to thrive. Peripheral smear showed blasts with normocytic hypochromic anemia and thrombocytopenia and the Refrigeration test was positive. We report 3 cases of Chylomicronemia syndrome in the last 2 years.

Lipemia Retinalis in a Patient with Diabetic Retinopathy

PURPOSE: To report a case of lipemia retinalis in a patient with diabetes. CASE SUMMARY: A 27-year-old female with type 2 diabetes visited our clinic with visual disturbance in her left eye while being followed up from a pars plana vitrectomy in her right eye for proliferative diabetic retinopathy. On fundus examination of both eyes, the retinal vessels were creamy white and the retinal veins were undistinguishable from the retinal arteries. The serum triglyceride level was 2,676 mg/dL. The patient was asymptomatic except for visual impairment due to vitreous hemorrhage in her left eye. The patient was diagnosed with lipemia retinalis and chylomicronemia syndrome. After controlling the triglyceride level, funduscopic findings in the both eyes were improved. However, the visual acuity in her right eye remained unchanged. CONCLUSIONS: Lipemia retinalis can be a sign of a systemic condition although it may not affect visual acuity. Fundus examination may be a useful tool in the early diagnosis of hyperlipidemia.

Familial Chylomicronemia Syndrome Presenting With Acute Necrotizing Pancreatitis in a Five Month Infant.

Familial chylomicronemia syndrome (FCS) is a rare disease characterized by severe fasting hypertriglyceridemia and chylomicronemia, which is inherited in an autosomal recessive manner. It is arisen from apolipoprotein C-ll deficiency or Lipoprotein Lipase(LPL) Deficiency.We report a 5-month-old male infant FCS presenting with acute abdominal pain and post surgical diagnosis of acute necrotizing pancreatitis.

A Case of Lipoprotein Lipase Deficiency inan Infant with Recurrent Pancreatitis / 대한소아소화기영양학회지

Familial chylomicronemia syndrome is a rare disorder characterized by severe hypertriglyceridemia and fasting chylomicronemia. Causes of the syndrome include lipoprotein lipase (LPL) deficiency, apolipoprotein C-II deficiency, or the presence of inhibitors to LPL. We managed a 3-month-old girl who had recurrent acute pancreatitis caused by chylomicronemia. We report the first case of familial chylomicronemia in Korea caused by LPL deficiency in an infant with recurrent acute pancreatitis.