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Suzuki T, Kurano M, Isono A, Uchino T, Sayama Y, Tomomitsu H, Mayumi D, Shibayama R, Sekiguchi T, Edo N, Uno-Eder K, Uno K, Morita K, Ishikawa T, Tsukamoto K. Genetic and biochemical analysis of severe hypertriglyceridemia complicated with acute pancreatitis or with low post-heparin lipoprotein lipase mass. Endocr J 2024; 71:447-460. [PMID: 38346769 DOI: 10.1507/endocrj.ej23-0438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/24/2024] Open
Abstract
Severe hypertriglyceridemia is a pathological condition caused by genetic factors alone or in combination with environmental factors, sometimes leading to acute pancreatitis (AP). In this study, exome sequencing and biochemical analyses were performed in 4 patients with hypertriglyceridemia complicated by obesity or diabetes with a history of AP or decreased post-heparin LPL mass. In a patient with a history of AP, SNP rs199953320 resulting in LMF1 nonsense mutation and APOE rs7412 causing apolipoprotein E2 were both found in heterozygous form. Three patients were homozygous for APOA5 rs2075291, and one was heterozygous. ELISA and Western blot analysis of the serum revealed the existence of apolipoprotein A-V in the lipoprotein-free fraction regardless of the presence or absence of rs2075291; furthermore, the molecular weight of apolipoprotein A-V was different depending on the class of lipoprotein or lipoprotein-free fraction. Lipidomics analysis showed increased serum levels of sphingomyelin and many classes of glycerophospholipid; however, when individual patients were compared, the degree of increase in each class of phospholipid among cases did not coincide with the increases seen in total cholesterol and triglycerides. Moreover, phosphatidylcholine, lysophosphatidylinositol, and sphingomyelin levels tended to be higher in patients who experienced AP than those who did not, suggesting that these phospholipids may contribute to the onset of AP. In summary, this study revealed a new disease-causing gene mutation in LMF1, confirmed an association between overlapping of multiple gene mutations and severe hypertriglyceridemia, and suggested that some classes of phospholipid may be involved in the pathogenesis of AP.
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Affiliation(s)
- Takashi Suzuki
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Makoto Kurano
- Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Endowed Chairs Department of Clinical Research Medicine, Teikyo University, Tokyo 173-8605, Japan
| | - Akari Isono
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Takuya Uchino
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Yohei Sayama
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Honami Tomomitsu
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Daiki Mayumi
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Ruriko Shibayama
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Toru Sekiguchi
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Naoki Edo
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Kiyoko Uno-Eder
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
- Teikyo Academic Research Center, Teikyo University, Tokyo 173-8605, Japan
| | - Kenji Uno
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Koji Morita
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Toshio Ishikawa
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Kazuhisa Tsukamoto
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan
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Jiang S, Ren Z, Yang Y, Liu Q, Zhou S, Xiao Y. The GPIHBP1-LPL complex and its role in plasma triglyceride metabolism: Insights into chylomicronemia. Biomed Pharmacother 2023; 169:115874. [PMID: 37951027 DOI: 10.1016/j.biopha.2023.115874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 11/13/2023] Open
Abstract
GPIHBP1 is a protein found in the endothelial cells of capillaries that is anchored by glycosylphosphatidylinositol and binds to high-density lipoproteins. GPIHBP1 attaches to lipoprotein lipase (LPL), subsequently carrying the enzyme and anchoring it to the capillary lumen. Enabling lipid metabolism is essential for the marginalization of lipoproteins alongside capillaries. Studies underscore the significance of GPIHBP1 in transporting, stabilizing, and aiding in the marginalization of LPL. The intricate interplay between GPIHBP1 and LPL has provided novel insights into chylomicronemia in recent years. Mutations hindering the formation or reducing the efficiency of the GPIHBP1-LPL complex are central to the onset of chylomicronemia. This review delves into the structural nuances of the GPIHBP1-LPL interaction, the consequences of mutations in the complex leading to chylomicronemia, and cutting-edge advancements in chylomicronemia treatment.
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Affiliation(s)
- Shali Jiang
- Department of Cardiovascular Medicine, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, PR China; Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, PR China
| | - Zhuoqun Ren
- Department of Cardiovascular Medicine, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, PR China; Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, PR China
| | - Yutao Yang
- Department of Cardiovascular Medicine, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, PR China; Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, PR China
| | - Qiming Liu
- Department of Cardiovascular Medicine, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, PR China
| | - Shenghua Zhou
- Department of Cardiovascular Medicine, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, PR China
| | - Yichao Xiao
- Department of Cardiovascular Medicine, Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, PR China.
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Kurooka N, Eguchi J, Wada J. Role of glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 in hypertriglyceridemia and diabetes. J Diabetes Investig 2023; 14:1148-1156. [PMID: 37448184 PMCID: PMC10512915 DOI: 10.1111/jdi.14056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 06/25/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023] Open
Abstract
In diabetes, the impairment of insulin secretion and insulin resistance contribute to hypertriglyceridemia, as the enzymatic activity of lipoprotein lipase (LPL) depends on insulin action. The transport of LPL to endothelial cells and its enzymatic activity are maintained by the formation of lipolytic complex depending on the multiple positive (glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 [GPIHBP1], apolipoprotein C-II [APOC2], APOA5, heparan sulfate proteoglycan [HSPG], lipase maturation factor 1 [LFM1] and sel-1 suppressor of lin-12-like [SEL1L]) and negative regulators (APOC1, APOC3, angiopoietin-like proteins [ANGPTL]3, ANGPTL4 and ANGPTL8). Among the regulators, GPIHBP1 is a crucial molecule for the translocation of LPL from parenchymal cells to the luminal surface of capillary endothelial cells, and maintenance of lipolytic activity; that is, hydrolyzation of triglyceride into free fatty acids and monoglyceride, and conversion from chylomicron to chylomicron remnant in the exogenous pathway and from very low-density lipoprotein to low-density lipoprotein in the endogenous pathway. The null mutation of GPIHBP1 causes severe hypertriglyceridemia and pancreatitis, and GPIGBP1 autoantibody syndrome also causes severe hypertriglyceridemia and recurrent episodes of acute pancreatitis. In patients with type 2 diabetes, the elevated serum triglyceride levels negatively correlate with circulating LPL levels, and positively with circulating APOC1, APOC3, ANGPTL3, ANGPTL4 and ANGPTL8 levels. In contrast, circulating GPIHBP1 levels are not altered in type 2 diabetes patients with higher serum triglyceride levels, whereas they are elevated in type 2 diabetes patients with diabetic retinopathy and nephropathy. The circulating regulators of lipolytic complex might be new biomarkers for lipid and glucose metabolism, and diabetic vascular complications.
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Affiliation(s)
- Naoko Kurooka
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Faculty of Medicine, Dentistry and Pharmaceutical SciencesOkayama UniversityOkayamaJapan
| | - Jun Eguchi
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Faculty of Medicine, Dentistry and Pharmaceutical SciencesOkayama UniversityOkayamaJapan
| | - Jun Wada
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Faculty of Medicine, Dentistry and Pharmaceutical SciencesOkayama UniversityOkayamaJapan
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Sustar U, Groselj U, Khan SA, Shafi S, Khan I, Kovac J, Bizjan BJ, Battelino T, Sadiq F. A homozygous variant in the GPIHBP1 gene in a child with severe hypertriglyceridemia and a systematic literature review. Front Genet 2022; 13:983283. [PMID: 36051701 PMCID: PMC9424485 DOI: 10.3389/fgene.2022.983283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Due to nonspecific symptoms, rare dyslipidaemias are frequently misdiagnosed, overlooked, and undertreated, leading to increased risk for severe cardiovascular disease, pancreatitis and/or multiple organ failures before diagnosis. Better guidelines for the recognition and early diagnosis of rare dyslipidaemias are urgently required. Methods: Genomic DNA was isolated from blood samples of a Pakistani paediatric patient with hypertriglyceridemia, and from his parents and siblings. Next-generation sequencing (NGS) was performed, and an expanded dyslipidaemia panel was employed for genetic analysis. Results: The NGS revealed the presence of a homozygous missense pathogenic variant c.230G>A (NM_178172.6) in exon 3 of the GPIHBP1 (glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1) gene resulting in amino acid change p.Cys77Tyr (NP_835466.2). The patient was 5.5 years old at the time of genetic diagnosis. The maximal total cholesterol and triglyceride levels were measured at the age of 10 months (850.7 mg/dl, 22.0 mmol/L and 5,137 mg/dl, 58.0 mmol/L, respectively). The patient had cholesterol deposits at the hard palate, eruptive xanthomas, lethargy, poor appetite, and mild splenomegaly. Both parents and sister were heterozygous for the familial variant in the GPIHBP1 gene. Moreover, in the systematic review, we present 62 patients with pathogenic variants in the GPIHBP1 gene and clinical findings, associated with hyperlipoproteinemia. Conclusion: In a child with severe hypertriglyceridemia, we identified a pathogenic variant in the GPIHBP1 gene causing hyperlipoproteinemia (type 1D). In cases of severe elevations of plasma cholesterol and/or triglycerides genetic testing for rare dyslipidaemias should be performed as soon as possible for optimal therapy and patient management.
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Affiliation(s)
- Ursa Sustar
- Department of Endocrinology, Diabetes and Metabolism, University Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Urh Groselj
- Department of Endocrinology, Diabetes and Metabolism, University Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, CA, United States
- *Correspondence: Urh Groselj, ; Fouzia Sadiq,
| | - Sabeen Abid Khan
- Department of Paediatrics, Shifa College of Medicine, Shifa Tameer-e-Millat University, Islamabad, Pakistan
| | - Saeed Shafi
- Department of Anatomy, Shifa Tameer-e-Millat University, Islamabad, Pakistan
| | - Iqbal Khan
- Department of Vascular Surgery, Shifa International Hospital, Islamabad, Pakistan
- Department of Vascular Surgery, Shifa Tameer-e-Millat University, Islamabad, Pakistan
| | - Jernej Kovac
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Clinical Institute for Special Laboratory Diagnostics, University Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Barbara Jenko Bizjan
- Clinical Institute for Special Laboratory Diagnostics, University Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Tadej Battelino
- Department of Endocrinology, Diabetes and Metabolism, University Children’s Hospital, University Medical Centre Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Fouzia Sadiq
- Directorate of Research, Shifa Tameer-e-Millat University, Islamabad, Pakistan
- *Correspondence: Urh Groselj, ; Fouzia Sadiq,
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CREBH Systemically Regulates Lipid Metabolism by Modulating and Integrating Cellular Functions. Nutrients 2021; 13:nu13093204. [PMID: 34579081 PMCID: PMC8472586 DOI: 10.3390/nu13093204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/13/2021] [Accepted: 09/13/2021] [Indexed: 12/11/2022] Open
Abstract
Cyclic AMP-responsive element-binding protein H (CREBH, encoded by CREB3L3) is a membrane-bound transcriptional factor expressed in the liver and small intestine. The activity of CREBH is regulated not only at the transcriptional level but also at the posttranslational level. CREBH governs triglyceride metabolism in the liver by controlling gene expression, with effects including the oxidation of fatty acids, lipophagy, and the expression of apolipoproteins related to the lipoprotein lipase activation and suppression of lipogenesis. The activation and functions of CREBH are controlled in response to the circadian rhythm. On the other hand, intestinal CREBH downregulates the absorption of lipids from the diet. CREBH deficiency in mice leads to severe hypertriglyceridemia and fatty liver in the fasted state and while feeding a high-fat diet. Therefore, when crossing CREBH knockout (KO) mice with an atherosclerosis model, low-density lipoprotein receptor KO mice, these mice exhibit severe atherosclerosis. This phenotype is seen in both liver- and small intestine-specific CREBH KO mice, suggesting that CREBH controls lipid homeostasis in an enterohepatic interaction. This review highlights that CREBH has a crucial role in systemic lipid homeostasis to integrate cellular functions related to lipid metabolism.
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A novel GPIHBP1 mutation related to familial chylomicronemia syndrome: A series of cases. Atherosclerosis 2021; 322:31-38. [PMID: 33706081 DOI: 10.1016/j.atherosclerosis.2021.02.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 02/10/2021] [Accepted: 02/18/2021] [Indexed: 01/13/2023]
Abstract
BACKGROUND AND AIMS GPIHBP1 is an accessory protein of lipoprotein lipase (LPL) essential for its functioning. Mutations in the GPIHBP1 gene cause a deficit in the action of LPL, leading to severe hypertriglyceridemia and increased risk for acute pancreatitis. METHODS We describe twelve patients (nine women) with a novel homozygous mutation in intron 2 of the GPIHBP1 gene. RESULTS All patients were from the Northeastern region of Brazil and presented the same homozygous variant located in a highly conserved 3' splicing acceptor site of the GPIHBP1 gene. This new variant was named c.182-1G > T, according to HGVS recommendations. We verified this new GPIHBP1 variant's effect by using the Human Splicing Finder (HSF) tool. This mutation changes the GPIHBP1 pre-mRNA processing and possibly causes the skipping of the exon 3 of the GPIHBP1 gene, affecting almost 50% of the cysteine-rich Lys6 GPIHBP1 domain. Patients presented with severe hypertriglyceridemia (2351 mg/dl [885-20600]) and low HDL (18 mg/dl [5-41). Four patients (33%) had a previous history of acute pancreatitis. CONCLUSIONS We describe a novel GPIHBP1 pathogenic intronic mutation of patients from the Northeast region of Brazil, suggesting the occurrence of a founder effect.
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Lin MH, Tian XH, Hao XL, Fei H, Yin JL, Yan DD, Li T. Management of a pregnant patient with chylomicronemia from a novel mutation in GPIHBP1: a case report. BMC Pregnancy Childbirth 2020; 20:272. [PMID: 32375710 PMCID: PMC7201967 DOI: 10.1186/s12884-020-02965-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 04/22/2020] [Indexed: 12/14/2022] Open
Abstract
Background Familial chylomicronemia syndrome (FCS) is a rare autosomal recessive lipid disorder often associated with recurrent episodes of pancreatitis. It is documented in most cases with FCS due to the mutations of key proteins in lipolysis, including LPL, APOC2, APOA5, LMF1 and GPIHBP1. Case presentation We report the successful management of a 35-year-old pregnant woman carrying a novel homozygous frameshift mutation c.48_49insGCGG (p.P17A fs*22) in the GPIHBP1 gene with previous severe episodes of acute pancreatitis triggered by pregnancy, resulting in adverse obstetrical outcomes. With careful monitoring, the patient underwent an uneventful pregnancy and delivered a baby with no anomalies. Conclusions The case report contributes to the understanding of GPIHBP1-deficient familial chylomicronemia syndrome (FCS) and highlights gestational management of FCS patient.
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Affiliation(s)
- Min-Huan Lin
- Department of Obstetrics & Gynecology, the Seventh Affiliated Hospital of Sun Yat-Sen University, 628 Zhenyuan Road, Guangming District, Shenzhen, China
| | - Xiao-Hui Tian
- Department of Obstetrics & Gynecology, the Seventh Affiliated Hospital of Sun Yat-Sen University, 628 Zhenyuan Road, Guangming District, Shenzhen, China
| | - Xiu-Lan Hao
- Department of Obstetrics & Gynecology, the Seventh Affiliated Hospital of Sun Yat-Sen University, 628 Zhenyuan Road, Guangming District, Shenzhen, China
| | - Hui Fei
- Department of Obstetrics & Gynecology, the Seventh Affiliated Hospital of Sun Yat-Sen University, 628 Zhenyuan Road, Guangming District, Shenzhen, China
| | - Jian-Lan Yin
- Department of Obstetrics & Gynecology, the Seventh Affiliated Hospital of Sun Yat-Sen University, 628 Zhenyuan Road, Guangming District, Shenzhen, China
| | - Dan-Dan Yan
- Department of Obstetrics & Gynecology, the Seventh Affiliated Hospital of Sun Yat-Sen University, 628 Zhenyuan Road, Guangming District, Shenzhen, China
| | - Tian Li
- Department of Obstetrics & Gynecology, the Seventh Affiliated Hospital of Sun Yat-Sen University, 628 Zhenyuan Road, Guangming District, Shenzhen, China.
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Matsunaga A, Nagashima M, Yamagishi H, Saku K. Variants of Lipid-Related Genes in Adult Japanese Patients with Severe Hypertriglyceridemia. J Atheroscler Thromb 2020; 27:1264-1277. [PMID: 32115487 PMCID: PMC7840158 DOI: 10.5551/jat.51540] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Aim: Hypertriglyceridemia is a type of dyslipidemia that contributes to atherosclerosis and coronary heart disease. Variants in lipoprotein lipase (LPL), apolipoprotein CII (APOC2), apolipoprotein AV (APOA5), glycosylphosphatidylinositol- anchored high-density lipoprotein-binding protein 1 (GPIHBP1), lipase maturation factor 1 (LMF1), and glucokinase regulator (GCKR) are responsible for hypertriglyceridemia. We investigated the molecular basis of severe hypertriglyceridemia in adult patients referred to the Clinical Laboratory at Fukuoka University Hospital. Methods: Twenty-three adult patients with severe hypertriglyceridemia (> 1,000 mg/dL, 11.29 mmol/L) were selected. The coding regions of candidate genes were sequenced by next-generation sequencing. Forty-nine genes reportedly associated with hypertriglyceridemia were analyzed. Results: In the 23 patients, we detected 70 variants: 28 rare and 42 common ones. Among the 28 rare variants with < 1% allele frequency, p.I4533L in APOB, p.M490I in MLXIPL, p.L152M in NCAN, and p.S264T in TIMD4 were novel. We did not observe single gene homozygous or compound heterozygous disease-causing rare variants in any of the 23 hypertriglyceridemia cases. However, in silico algorithms and previous reports indicated that five rare variants, APOA5 (p.T184S), GCKR (c.354 + 1G>A), LMF1 (p.G410R), and LRP1 (p.G813R; p.R2173Q), and seven common variants, APOA5 (pG185C), APOE (p.C130R; p.E262K/p.E263K), GCKR (p.V103M), GPIHBP1 (p.C14F), LRP1 (p.Y4054F), and MLXIPL (p.Q241H), can cause hypertriglyceridemia. However, all five disease-causing rare variants detected in this study were heterozygous. Conclusions: The prevalence of disease-causing rare variants in candidate genes in severe hypertriglyceridemia patients was low. The major causes of severe hypertriglyceridemia were not single gene abnormalities, but involved multiple gene variations and environmental factors.
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Affiliation(s)
- Akira Matsunaga
- Department of Laboratory Medicine, Fukuoka University School of Medicine
| | - Mariko Nagashima
- Department of Laboratory Medicine, Fukuoka University School of Medicine
| | - Hideko Yamagishi
- Department of Laboratory Medicine, Fukuoka University School of Medicine
| | - Keijiro Saku
- Department of Cardiology, Fukuoka University School of Medicine
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Young SG, Fong LG, Beigneux AP, Allan CM, He C, Jiang H, Nakajima K, Meiyappan M, Birrane G, Ploug M. GPIHBP1 and Lipoprotein Lipase, Partners in Plasma Triglyceride Metabolism. Cell Metab 2019; 30:51-65. [PMID: 31269429 PMCID: PMC6662658 DOI: 10.1016/j.cmet.2019.05.023] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Lipoprotein lipase (LPL), identified in the 1950s, has been studied intensively by biochemists, physiologists, and clinical investigators. These efforts uncovered a central role for LPL in plasma triglyceride metabolism and identified LPL mutations as a cause of hypertriglyceridemia. By the 1990s, with an outline for plasma triglyceride metabolism established, interest in triglyceride metabolism waned. In recent years, however, interest in plasma triglyceride metabolism has awakened, in part because of the discovery of new molecules governing triglyceride metabolism. One such protein-and the focus of this review-is GPIHBP1, a protein of capillary endothelial cells. GPIHBP1 is LPL's essential partner: it binds LPL and transports it to the capillary lumen; it is essential for lipoprotein margination along capillaries, allowing lipolysis to proceed; and it preserves LPL's structure and activity. Recently, GPIHBP1 was the key to solving the structure of LPL. These developments have transformed the models for intravascular triglyceride metabolism.
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Affiliation(s)
- Stephen G Young
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Loren G Fong
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Anne P Beigneux
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Christopher M Allan
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Cuiwen He
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Haibo Jiang
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; School of Molecular Sciences, University of Western Australia, Crawley 6009, Australia
| | - Katsuyuki Nakajima
- Department of Clinical Laboratory Medicine, Gunma University Graduate School of Department of Medicine, Maebashi, Gunma 371-0805, Japan
| | - Muthuraman Meiyappan
- Discovery Therapeutics, Takeda Pharmaceutical Company Ltd., Cambridge, MA 02142, USA
| | - Gabriel Birrane
- Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Michael Ploug
- Finsen Laboratory, Rigshospitalet, Copenhagen DK-2200, Denmark; Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen DK-2200, Denmark.
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Liu X, Li J, Liao J, Wang H, Huang X, Dong Z, Shen Q, Zhang L, Wang Y, Kong W, Liu G, Huang W. Gpihbp1 deficiency accelerates atherosclerosis and plaque instability in diabetic Ldlr-/- mice. Atherosclerosis 2019; 282:100-109. [PMID: 30721842 DOI: 10.1016/j.atherosclerosis.2019.01.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 12/29/2018] [Accepted: 01/15/2019] [Indexed: 01/17/2023]
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11
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Liu C, Li L, Guo D, Lv Y, Zheng X, Mo Z, Xie W. Lipoprotein lipase transporter GPIHBP1 and triglyceride-rich lipoprotein metabolism. Clin Chim Acta 2018; 487:33-40. [PMID: 30218660 DOI: 10.1016/j.cca.2018.09.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/11/2018] [Accepted: 09/11/2018] [Indexed: 02/05/2023]
Abstract
Increased plasma triglyceride serves as an independent risk factor for cardiovascular disease (CVD). Lipoprotein lipase (LPL), which hydrolyzes circulating triglyceride, plays a crucial role in normal lipid metabolism and energy balance. Hypertriglyceridemia is possibly caused by gene mutations resulting in LPL dysfunction. There are many factors that both positively and negatively interact with LPL thereby impacting TG lipolysis. Glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1), a newly identified factor, appears essential for transporting LPL to the luminal side of the blood vessel and offering a platform for TG hydrolysis. Numerous lines of evidence indicate that GPIHBP1 exerts distinct functions and plays diverse roles in human triglyceride-rich lipoprotein (TRL) metabolism. In this review, we discuss the GPIHBP1 gene, protein, its expression and function and subsequently focus on its regulation and provide critical evidence supporting its role in TRL metabolism. Underlying mechanisms of action are highlighted, additional studies discussed and potential therapeutic targets reviewed.
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Affiliation(s)
- Chuhao Liu
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang 421001, Hunan, China; 2016 Class of Excellent Doctor, University of South China, Hengyang 421001, Hunan, China
| | - Liang Li
- Department of Pathophysiology, University of South China, Hengyang 421001, Hunan, China
| | - Dongming Guo
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang 421001, Hunan, China
| | - Yuncheng Lv
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang 421001, Hunan, China
| | - XiLong Zheng
- Department of Biochemistry and Molecular Biology, The Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, The University of Calgary, Health Sciences Center, 3330 Hospital Dr NW, Calgary T2N 4N1, Alberta, Canada; Key Laboratory of Molecular Targets & Clinical Pharmacology, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou 511436, Guangdong, China
| | - Zhongcheng Mo
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang 421001, Hunan, China.
| | - Wei Xie
- Clinical Anatomy & Reproductive Medicine Application Institute, University of South China, Hengyang 421001, Hunan, China.
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12
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CREBH Regulates Systemic Glucose and Lipid Metabolism. Int J Mol Sci 2018; 19:ijms19051396. [PMID: 29738435 PMCID: PMC5983805 DOI: 10.3390/ijms19051396] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 04/30/2018] [Accepted: 05/06/2018] [Indexed: 12/23/2022] Open
Abstract
The cyclic adenosine monophosphate (cAMP)-responsive element-binding protein H (CREBH, encoded by CREB3L3) is a membrane-bound transcriptional factor that primarily localizes in the liver and small intestine. CREBH governs triglyceride metabolism in the liver, which mediates the changes in gene expression governing fatty acid oxidation, ketogenesis, and apolipoproteins related to lipoprotein lipase (LPL) activation. CREBH in the small intestine reduces cholesterol transporter gene Npc1l1 and suppresses cholesterol absorption from diet. A deficiency of CREBH in mice leads to severe hypertriglyceridemia, fatty liver, and atherosclerosis. CREBH, in synergy with peroxisome proliferator-activated receptor α (PPARα), has a crucial role in upregulating Fgf21 expression, which is implicated in metabolic homeostasis including glucose and lipid metabolism. CREBH binds to and functions as a co-activator for both PPARα and liver X receptor alpha (LXRα) in regulating gene expression of lipid metabolism. Therefore, CREBH has a crucial role in glucose and lipid metabolism in the liver and small intestine.
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13
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Lee CJ, Oum CY, Lee Y, Park S, Kang SM, Choi D, Jang Y, Lee JH, Lee SH. Variants of Lipolysis-Related Genes in Korean Patients with Very High Triglycerides. Yonsei Med J 2018; 59:148-153. [PMID: 29214790 PMCID: PMC5725353 DOI: 10.3349/ymj.2018.59.1.148] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 09/01/2017] [Accepted: 09/07/2017] [Indexed: 11/27/2022] Open
Abstract
We investigated the prevalence and characteristics of variants of five lipolysis-related genes in Korean patients with very high triglycerides (TGs). Twenty-six patients with TG levels >885 mg/dL were selected from 13545 Korean subjects. Five candidate genes, LPL, APOC2, GPIHBP1, APOA5, and LMF1, were sequenced by targeted next-generation sequencing. Predictions of functional effects were performed and matched against public databases of variants. Ten rare variants of three genes were found in nine (34.6%) patients (three in LPL, four in APOA5, and three in LMF1). Five were novel and all variants were suspected of being disease-causing. Nine were heterozygous, and one (3.8%) had a homozygous rare variant of LPL. Six common variants of four genes were observed in 25 (96.2%) patients (one in LPL, one in GPIHBP1, two in APOA5, and two in LMF1). The c.G41T variant of GPIHBP1 and c.G533T variant of APOA5 were most frequent and found in 15 (57.7%) and 14 (53.8%) patients, respectively. Rare homozygous variants of the genes were very uncommon, while diverse rare heterozygous variants were commonly identified. Taken together, most study subjects may be manifesting the combined effects of rare heterozygous variants and common variants.
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Affiliation(s)
- Chan Joo Lee
- Division of Cardiology, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
- Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Chi Yoon Oum
- Department of Biostatistics and Computing, The Graduate School, Yonsei University, Seoul, Korea
| | - Yunbeom Lee
- Department of Medicine, Graduate School, Kyung Hee University, Seoul, Korea
- Department of Clinical Pharmacology and Therapeutics, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Sungha Park
- Division of Cardiology, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
- Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Seok Min Kang
- Division of Cardiology, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
- Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Donghoon Choi
- Division of Cardiology, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
- Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Yangsoo Jang
- Division of Cardiology, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
- Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Ji Hyun Lee
- Department of Clinical Pharmacology and Therapeutics, College of Medicine, Kyung Hee University, Seoul, Korea.
| | - Sang Hak Lee
- Division of Cardiology, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
- Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Korea.
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14
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Allan CM, Larsson M, Jung RS, Ploug M, Bensadoun A, Beigneux AP, Fong LG, Young SG. Mobility of "HSPG-bound" LPL explains how LPL is able to reach GPIHBP1 on capillaries. J Lipid Res 2016; 58:216-225. [PMID: 27811232 DOI: 10.1194/jlr.m072520] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 10/31/2016] [Indexed: 12/22/2022] Open
Abstract
In mice lacking glycosylphosphatidylinositol-anchored high density lipoprotein binding protein 1 (GPIHBP1), the LPL secreted by adipocytes and myocytes remains bound to heparan sulfate proteoglycans (HSPGs) on all cells within tissues. That observation raises a perplexing issue: Why isn't the freshly secreted LPL in wild-type mice captured by the same HSPGs, thereby preventing LPL from reaching GPIHBP1 on capillaries? We hypothesized that LPL-HSPG interactions are transient, allowing the LPL to detach and move to GPIHBP1 on capillaries. Indeed, we found that LPL detaches from HSPGs on cultured cells and moves to: 1) soluble GPIHBP1 in the cell culture medium; 2) GPIHBP1-coated agarose beads; and 3) nearby GPIHBP1-expressing cells. Movement of HSPG-bound LPL to GPIHBP1 did not occur when GPIHBP1 contained a Ly6 domain missense mutation (W109S), but was almost normal when GPIHBP1's acidic domain was mutated. To test the mobility of HSPG-bound LPL in vivo, we injected GPIHBP1-coated agarose beads into the brown adipose tissue of GPIHBP1-deficient mice. LPL moved quickly from HSPGs on adipocytes to GPIHBP1-coated beads, thereby depleting LPL stores on the surface of adipocytes. We conclude that HSPG-bound LPL in the interstitial spaces of tissues is mobile, allowing the LPL to move to GPIHBP1 on endothelial cells.
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Affiliation(s)
- Christopher M Allan
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Mikael Larsson
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Rachel S Jung
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Michael Ploug
- Finsen Laboratory, Rigshospitalet, DK-2200 Copenhagen N, Denmark and Biotech Research and Innovation Centre (BRIC), University of Copenhagen, DK-220 Copenhagen N, Denmark
| | - André Bensadoun
- Division of Nutritional Science, Cornell University, Ithaca, NY 14853
| | - Anne P Beigneux
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Loren G Fong
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095
| | - Stephen G Young
- Departments of Medicine University of California Los Angeles, Los Angeles, CA 90095 .,Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095
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15
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Allan CM, Larsson M, Hu X, He C, Jung RS, Mapar A, Voss C, Miyashita K, Machida T, Murakami M, Nakajima K, Bensadoun A, Ploug M, Fong LG, Young SG, Beigneux AP. An LPL-specific monoclonal antibody, 88B8, that abolishes the binding of LPL to GPIHBP1. J Lipid Res 2016; 57:1889-1898. [PMID: 27494936 DOI: 10.1194/jlr.m070813] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Indexed: 12/26/2022] Open
Abstract
LPL contains two principal domains: an amino-terminal catalytic domain (residues 1-297) and a carboxyl-terminal domain (residues 298-448) that is important for binding lipids and binding glycosylphosphatidylinositol-anchored high density lipoprotein binding protein 1 (GPIHBP1) (an endothelial cell protein that shuttles LPL to the capillary lumen). The LPL sequences required for GPIHBP1 binding have not been examined in detail, but one study suggested that sequences near LPL's carboxyl terminus (residues ∼403-438) were crucial. Here, we tested the ability of LPL-specific monoclonal antibodies (mAbs) to block the binding of LPL to GPIHBP1. One antibody, 88B8, abolished LPL binding to GPIHBP1. Consistent with those results, antibody 88B8 could not bind to GPIHBP1-bound LPL on cultured cells. Antibody 88B8 bound poorly to LPL proteins with amino acid substitutions that interfered with GPIHBP1 binding (e.g., C418Y, E421K). However, the sequences near LPL's carboxyl terminus (residues ∼403-438) were not sufficient for 88B8 binding; upstream sequences (residues 298-400) were also required. Additional studies showed that these same sequences are required for LPL binding to GPIHBP1. In conclusion, we identified an LPL mAb that binds to LPL's GPIHBP1-binding domain. The binding of both antibody 88B8 and GPIHBP1 to LPL depends on large segments of LPL's carboxyl-terminal domain.
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Affiliation(s)
- Christopher M Allan
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Mikael Larsson
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Xuchen Hu
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Cuiwen He
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Rachel S Jung
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Alaleh Mapar
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | - Constance Voss
- Departments of Medicine University of California Los Angeles, Los Angeles, CA
| | | | - Tetsuo Machida
- Gunma University, Graduate School of Medicine, Maebashi, Japan
| | - Masami Murakami
- Gunma University, Graduate School of Medicine, Maebashi, Japan
| | | | - André Bensadoun
- Division of Nutritional Science, Cornell University, Ithaca, NY
| | - Michael Ploug
- Finsen Laboratory, Rigshospitalet, Copenhagen N, Denmark; Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen N, Denmark
| | - Loren G Fong
- Departments of Medicine University of California Los Angeles, Los Angeles, CA.
| | - Stephen G Young
- Departments of Medicine University of California Los Angeles, Los Angeles, CA; Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA.
| | - Anne P Beigneux
- Departments of Medicine University of California Los Angeles, Los Angeles, CA.
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16
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Park JG, Xu X, Cho S, Lee AH. Loss of Transcription Factor CREBH Accelerates Diet-Induced Atherosclerosis in Ldlr-/- Mice. Arterioscler Thromb Vasc Biol 2016; 36:1772-81. [PMID: 27417587 DOI: 10.1161/atvbaha.116.307790] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 06/30/2016] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Liver-enriched transcription factor cAMP-responsive element-binding protein H (CREBH) regulates plasma triglyceride clearance by inducing lipoprotein lipase cofactors, such as apolipoprotein A-IV (apoA-IV), apoA-V, and apoC-II. CREBH also regulates apoA-I transcription. This study aims to determine whether CREBH has a role in lipoprotein metabolism and development of atherosclerosis. APPROACH AND RESULTS CREBH-deficient Creb3l3(-/-) mice were bred with Ldlr(-/-) mice creating Ldlr(-/-) Creb3l3(-/-) double knockout mice. Mice were fed on a high-fat and high-sucrose Western diet for 20 weeks. We showed that CREBH deletion in Ldlr(-/-) mice increased very low-density lipoprotein-associated triglyceride and cholesterol levels, consistent with the impairment of lipoprotein lipase-mediated triglyceride clearance in these mice. In contrast, high-density lipoprotein cholesterol levels were decreased in CREBH-deficient mice, which was associated with decreased production of apoA-I from the liver. The results indicate that CREBH directly activated Apoa1 gene transcription. Accompanied by the worsened atherogenic lipid profile, Ldlr(-/-) Creb3l3(-/-) mice developed significantly more atherosclerotic lesions in the aortas than Ldlr(-/-) mice. CONCLUSIONS We identified CREBH as an important regulator of lipoprotein metabolism and suggest that increasing hepatic CREBH activity may be a novel strategy for prevention and treatment of atherosclerosis.
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Affiliation(s)
- Jong-Gil Park
- From the Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY
| | - Xu Xu
- From the Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY
| | - Sungyun Cho
- From the Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY
| | - Ann-Hwee Lee
- From the Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY.
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17
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Patni N, Brothers J, Xing C, Garg A. Type 1 hyperlipoproteinemia in a child with large homozygous deletion encompassing GPIHBP1. J Clin Lipidol 2016; 10:1035-1039.e2. [DOI: 10.1016/j.jacl.2016.04.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 03/30/2016] [Accepted: 04/03/2016] [Indexed: 01/12/2023]
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18
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Fong LG, Young SG, Beigneux AP, Bensadoun A, Oberer M, Jiang H, Ploug M. GPIHBP1 and Plasma Triglyceride Metabolism. Trends Endocrinol Metab 2016; 27:455-469. [PMID: 27185325 PMCID: PMC4927088 DOI: 10.1016/j.tem.2016.04.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 04/26/2016] [Accepted: 04/27/2016] [Indexed: 10/21/2022]
Abstract
GPIHBP1, a GPI-anchored protein in capillary endothelial cells, is crucial for the lipolytic processing of triglyceride-rich lipoproteins (TRLs). GPIHBP1 shuttles lipoprotein lipase (LPL) to its site of action in the capillary lumen and is essential for the margination of TRLs along capillaries - such that lipolytic processing can proceed. GPIHBP1 also reduces the unfolding of the LPL catalytic domain, thereby stabilizing LPL catalytic activity. Many different GPIHBP1 mutations have been identified in patients with severe hypertriglyceridemia (chylomicronemia), the majority of which interfere with folding of the protein and abolish its capacity to bind and transport LPL. The discovery of GPIHBP1 has substantially revised our understanding of intravascular triglyceride metabolism but has also raised many new questions for future research.
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Affiliation(s)
- Loren G Fong
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
| | - Stephen G Young
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
| | - Anne P Beigneux
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - André Bensadoun
- Division of Nutritional Science, Cornell University, Ithaca, NY 14853, USA
| | - Monika Oberer
- Institute of Molecular Biosciences, University of Graz and BioTechMed, Graz, Austria
| | - Haibo Jiang
- Centre for Microscopy, Characterisation, and Analysis, The University of Western Australia
| | - Michael Ploug
- Finsen Laboratory, Rigshospitalet, 2200 Copenhagen N, Denmark; Biotech Research and Innovation Centre (BRIC), University of Copenhagen, 220 Copenhagen N, Denmark.
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19
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Clinical and genetic features of 3 patients with familial chylomicronemia due to mutations in GPIHBP1 gene. J Clin Lipidol 2016; 10:915-921.e4. [PMID: 27578123 DOI: 10.1016/j.jacl.2016.03.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/11/2016] [Accepted: 03/12/2016] [Indexed: 12/30/2022]
Abstract
BACKGROUND Familial chylomicronemia is a recessive disorder that may be due to mutations in lipoprotein lipase (LPL) and in other proteins such as apolipoprotein C-II and apolipoprotein A-V (activators of LPL), GPIHBP1 (the molecular platform required for LPL activity on endothelial surface), and LMF1 (a factor required for intracellular formation of active LPL). METHODS We sequenced the familial chylomicronemia candidate genes in 2 adult females presenting long-standing hypertriglyceridemia and a history of acute pancreatitis. RESULTS Both probands had plasma triglyceride >10 mmol/L but no mutations in the LPL gene. The sequence of the other candidate genes showed that one patient was homozygous for a novel missense mutation p.(Cys83Arg), and the other was homozygous for a previously reported nonsense mutation p.(Cys 89*), respectively, in GPIHBP1. Family screening showed that the hypertriglyceridemic brother of the p.(Cys83Arg) homozygote was also homozygous for this mutation. He had no history of pancreatitis. The p.(Cys83Arg) heterozygous carriers had normal triglyceride levels. The substitution of a cysteine residue in the Ly6 domain of GPIHBP1 is predicted to abolish one of the disulfide bridges required to maintain the structure of GPIHBP1. The p.(Cys89*) mutation results in a truncated protein devoid of function. CONCLUSIONS Both mutant GPIHBP1 proteins are expected to be incapable of transferring LPL from the subendothelial space to the endothelial surface.
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20
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Update on the molecular biology of dyslipidemias. Clin Chim Acta 2016; 454:143-85. [DOI: 10.1016/j.cca.2015.10.033] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/24/2015] [Accepted: 10/30/2015] [Indexed: 12/20/2022]
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21
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Ariza MJ, Martínez-Hernández PL, Ibarretxe D, Rabacchi C, Rioja J, Grande-Aragón C, Plana N, Tarugi P, Olivecrona G, Calandra S, Valdivielso P. Novel mutations in the GPIHBP1 gene identified in 2 patients with recurrent acute pancreatitis. J Clin Lipidol 2015; 10:92-100.e1. [PMID: 26892125 DOI: 10.1016/j.jacl.2015.09.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 09/09/2015] [Accepted: 09/16/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND Glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1) has been demonstrated to be essential for the in vivo function of lipoprotein lipase (LPL), the major triglyceride (TG)-hydrolyzing enzyme involved in the intravascular lipolysis of TG-rich lipoproteins. Recently, loss-of-function mutations of GPIHBP1 have been reported as the cause of type I hyperlipoproteinemia in several patients. METHODS Two unrelated patients were referred to our Lipid Units because of a severe hypertriglyceridemia and recurrent pancreatitis. We measured LPL activity in postheparin plasma and serum ApoCII and sequenced LPL, APOC2, and GPIHBP1. RESULTS The 2 patients exhibited very low LPL activity not associated with mutations in LPL gene or with ApoCII deficiency. The sequence of GPIHBP1 revealed 2 novel point mutations. One patient (proband 1) was found to be homozygous for a C>A transversion in exon 3 resulting in the conversion of threonine to lysine at position 80 (p.Thr80Lys). The other patient (proband 2) was found to be homozygous for a G>T transversion in the third base of the ATG translation initiation codon in exon 1, resulting in the conversion of methionine to isoleucine (p.Met1Ile). CONCLUSION In conclusion, we have identified 2 novel GPIHBP1 missense mutations in 2 unrelated patients as the cause of their severe hypertriglyceridemia.
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Affiliation(s)
- María José Ariza
- Department of Medicine and Dermatology, Lipids and Atherosclerosis Laboratory, CIMES, University of Málaga, Málaga, Spain.
| | | | - Daiana Ibarretxe
- Vascular Medicine and Metabolism Unit, Research Unit on Lipids and Atherosclerosis, Sant Joan University Hospital, Universitat Rovira i Virgili, IISPV, Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Reus, Spain
| | - Claudio Rabacchi
- Department of Life Sciences, University of Modena & Reggio Emilia, Modena, Italy
| | - José Rioja
- Department of Medicine and Dermatology, Lipids and Atherosclerosis Laboratory, CIMES, University of Málaga, Málaga, Spain
| | | | - Nuria Plana
- Vascular Medicine and Metabolism Unit, Research Unit on Lipids and Atherosclerosis, Sant Joan University Hospital, Universitat Rovira i Virgili, IISPV, Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Reus, Spain
| | - Patrizia Tarugi
- Department of Life Sciences, University of Modena & Reggio Emilia, Modena, Italy
| | - Gunilla Olivecrona
- Department of Medical Biosciences, Physiological Chemistry, Umeå University, Umeå, Sweden
| | - Sebastiano Calandra
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena & Reggio Emilia Modena, Italy
| | - Pedro Valdivielso
- Department of Medicine and Dermatology, Lipids and Atherosclerosis Laboratory, CIMES, University of Málaga, Málaga, Spain; Internal Medicine Unit, Virgen de la Victoria University Hospital, Málaga, Spain
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22
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Xie SL, Chen TZ, Huang XL, Chen C, Jin R, Huang ZM, Zhou MT. Genetic Variants Associated with Gestational Hypertriglyceridemia and Pancreatitis. PLoS One 2015; 10:e0129488. [PMID: 26079787 PMCID: PMC4469420 DOI: 10.1371/journal.pone.0129488] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Accepted: 05/08/2015] [Indexed: 11/18/2022] Open
Abstract
Severe hypertriglyceridemia is a well-known cause of pancreatitis. Usually, there is a moderate increase in plasma triglyceride level during pregnancy. Additionally, certain pre-existing genetic traits may render a pregnant woman susceptible to development of severe hypertriglyceridemia and pancreatitis, especially in the third trimester. To elucidate the underlying mechanism of gestational hypertriglyceridemic pancreatitis, we undertook DNA mutation analysis of the lipoprotein lipase (LPL), apolipoprotein C2 (APOC2), apolipoprotein A5 (APOA5), lipase maturation factor 1 (LMF1), and glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1) genes in five unrelated pregnant Chinese women with severe hypertriglyceridemia and pancreatitis. DNA sequencing showed that three out of five patients had the same homozygous variation, p.G185C, in APOA5 gene. One patient had a compound heterozygous mutation, p.A98T and p.L279V, in LPL gene. Another patient had a compound heterozygous mutation, p.A98T & p.C14F in LPL and GPIHBP1 gene, respectively. No mutations were seen in APOC2 or LMF1 genes. All patients were diagnosed with partial LPL deficiency in non-pregnant state. As revealed in our study, genetic variants appear to play an important role in the development of severe gestational hypertriglyceridemia, and, p.G185C mutation in APOA5 gene appears to be the most common variant implicated in the Chinese population. Antenatal screening for mutations in susceptible women, combined with subsequent interventions may be invaluable in the prevention of potentially life threatening gestational hypertriglyceridemia-induced pancreatitis.
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Affiliation(s)
- Sai-Li Xie
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Tan-Zhou Chen
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xie-Lin Huang
- Ren-Ji Study, Wenzhou Medical University, Wenzhou, China
| | - Chao Chen
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Rong Jin
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhi-Ming Huang
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
- * E-mail: (M-TZ); (Z-MH)
| | - Meng-Tao Zhou
- The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
- * E-mail: (M-TZ); (Z-MH)
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23
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Tarailo-Graovac M, Sinclair G, Stockler-Ipsiroglu S, Van Allen M, Rozmus J, Shyr C, Biancheri R, Oh T, Sayson B, Lafek M, Ross CJ, Robinson WP, Wasserman WW, Rossi A, van Karnebeek CDM. The genotypic and phenotypic spectrum of PIGA deficiency. Orphanet J Rare Dis 2015; 10:23. [PMID: 25885527 PMCID: PMC4348372 DOI: 10.1186/s13023-015-0243-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 02/18/2015] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Phosphatidylinositol glycan biosynthesis class A protein (PIGA) is one of the enzymes involved in the biosynthesis of glycosylphosphatidylinositol (GPI) anchor proteins, which function as enzymes, adhesion molecules, complement regulators and co-receptors in signal transduction pathways. Until recently, only somatic PIGA mutations had been reported in patients with paroxysmal nocturnal hemoglobinuria (PNH), while germline mutations had not been observed, and were suspected to result in lethality. However, in just two years, whole exome sequencing (WES) analyses have identified germline PIGA mutations in male patients with XLIDD (X-linked intellectual developmental disorder) with a wide spectrum of clinical presentations. METHODS AND RESULTS Here, we report on a new missense PIGA germline mutation [g.15342986C>T (p.S330N)] identified via WES followed by Sanger sequencing, in a Chinese male infant presenting with developmental arrest, infantile spasms, a pattern of lesion distribution on brain MRI resembling that typical of maple syrup urine disease, contractures, dysmorphism, elevated alkaline phosphatase, mixed hearing loss (a combination of conductive and sensorineural), liver dysfunction, mitochondrial complex I and V deficiency, and therapy-responsive dyslipidemia with confirmed lipoprotein lipase deficiency. X-inactivation studies showed skewing in the clinically unaffected carrier mother, and CD109 surface expression in patient fibroblasts was 57% of that measured in controls; together these data support pathogenicity of this mutation. Furthermore, we review all reported germline PIGA mutations (1 nonsense, 1 frameshift, 1 in-frame deletion, five missense) in 8 unrelated families. CONCLUSIONS Our case further delineates the heterogeneous phenotype of this condition for which we propose the term 'PIGA deficiency'. While the phenotypic spectrum is wide, it could be classified into two types (severe and less severe) with shared hallmarks of infantile spasms with hypsarrhythmia on EEG and profound XLIDD. In severe PIGA deficiency, as described in our patient, patients also present with dysmorphic facial features, multiple CNS abnormalities, such as thin corpus callosum and delayed myelination, as well as hypotonia and elevated alkaline phosphatase along with liver, renal, and cardiac involvement; its course is often fatal. The less severe form of PIGA deficiency does not involve facial dysmorphism and multiple CNS abnormalities; instead, patients present with milder IDD, treatable seizures and generally a longer lifespan.
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Affiliation(s)
- Maja Tarailo-Graovac
- Centre for Molecular Medicine and Therapeutics, Vancouver, Canada. .,Department of Medical Genetics, University of British Columbia, Vancouver, Canada. .,Treatable Intellectual Disability Endeavour in British Columbia, Vancouver, Canada.
| | - Graham Sinclair
- Treatable Intellectual Disability Endeavour in British Columbia, Vancouver, Canada. .,Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada. .,Biochemical Genetics Laboratory, Department of Pathology, BC Children's Hospital, University of British Columbia, Vancouver, Canada.
| | - Sylvia Stockler-Ipsiroglu
- Treatable Intellectual Disability Endeavour in British Columbia, Vancouver, Canada. .,Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada. .,Child & Family Research Institute, Vancouver, BC, Canada.
| | - Margot Van Allen
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada. .,Child & Family Research Institute, Vancouver, BC, Canada.
| | - Jacob Rozmus
- Division of Hematology, Oncology & BMT, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada. .,Child & Family Research Institute, Vancouver, BC, Canada.
| | - Casper Shyr
- Centre for Molecular Medicine and Therapeutics, Vancouver, Canada. .,Department of Medical Genetics, University of British Columbia, Vancouver, Canada. .,Treatable Intellectual Disability Endeavour in British Columbia, Vancouver, Canada.
| | - Roberta Biancheri
- Department of Paediatric Neurology, Children's Hospital Oxford, John Radcliffe Hospital, Oxford, UK.
| | - Tracey Oh
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada. .,Child & Family Research Institute, Vancouver, BC, Canada.
| | - Bryan Sayson
- Treatable Intellectual Disability Endeavour in British Columbia, Vancouver, Canada. .,Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada.
| | - Mirafe Lafek
- Treatable Intellectual Disability Endeavour in British Columbia, Vancouver, Canada. .,Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada.
| | - Colin J Ross
- Centre for Molecular Medicine and Therapeutics, Vancouver, Canada. .,Department of Medical Genetics, University of British Columbia, Vancouver, Canada. .,Treatable Intellectual Disability Endeavour in British Columbia, Vancouver, Canada. .,Child & Family Research Institute, Vancouver, BC, Canada.
| | - Wendy P Robinson
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada. .,Child & Family Research Institute, Vancouver, BC, Canada.
| | - Wyeth W Wasserman
- Centre for Molecular Medicine and Therapeutics, Vancouver, Canada. .,Department of Medical Genetics, University of British Columbia, Vancouver, Canada. .,Treatable Intellectual Disability Endeavour in British Columbia, Vancouver, Canada. .,Child & Family Research Institute, Vancouver, BC, Canada.
| | - Andrea Rossi
- Department of Neuroradiology, Istituto Giannina Gaslini, Via Gerolamo Gaslini 5, I-16147, Genoa, Italy.
| | - Clara D M van Karnebeek
- Centre for Molecular Medicine and Therapeutics, Vancouver, Canada. .,Treatable Intellectual Disability Endeavour in British Columbia, Vancouver, Canada. .,Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada. .,Child & Family Research Institute, Vancouver, BC, Canada.
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24
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Plengpanich W, Young SG, Khovidhunkit W, Bensadoun A, Karnman H, Ploug M, Gårdsvoll H, Leung CS, Adeyo O, Larsson M, Muanpetch S, Charoen S, Fong LG, Niramitmahapanya S, Beigneux AP. Multimerization of glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 (GPIHBP1) and familial chylomicronemia from a serine-to-cysteine substitution in GPIHBP1 Ly6 domain. J Biol Chem 2014; 289:19491-9. [PMID: 24847059 DOI: 10.1074/jbc.m114.558528] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
GPIHBP1, a glycosylphosphatidylinositol-anchored glycoprotein of microvascular endothelial cells, binds lipoprotein lipase (LPL) within the interstitial spaces and transports it across endothelial cells to the capillary lumen. The ability of GPIHBP1 to bind LPL depends on the Ly6 domain, a three-fingered structure containing 10 cysteines and a conserved pattern of disulfide bond formation. Here, we report a patient with severe hypertriglyceridemia who was homozygous for a GPIHBP1 point mutation that converted a serine in the GPIHBP1 Ly6 domain (Ser-107) to a cysteine. Two hypertriglyceridemic siblings were homozygous for the same mutation. All three homozygotes had very low levels of LPL in the preheparin plasma. We suspected that the extra cysteine in GPIHBP1-S107C might prevent the trafficking of the protein to the cell surface, but this was not the case. However, nearly all of the GPIHBP1-S107C on the cell surface was in the form of disulfide-linked dimers and multimers, whereas wild-type GPIHBP1 was predominantly monomeric. An insect cell GPIHBP1 expression system confirmed the propensity of GPIHBP1-S107C to form disulfide-linked dimers and to form multimers. Functional studies showed that only GPIHBP1 monomers bind LPL. In keeping with that finding, there was no binding of LPL to GPIHBP1-S107C in either cell-based or cell-free binding assays. We conclude that an extra cysteine in the GPIHBP1 Ly6 motif results in multimerization of GPIHBP1, defective LPL binding, and severe hypertriglyceridemia.
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Affiliation(s)
- Wanee Plengpanich
- From the Department of Medicine, Faculty of Medicine, Chulalongkorn University and Thai Red Cross Society, Bangkok 10330, Thailand
| | - Stephen G Young
- the Departments of Medicine and Human Genetics, UCLA, Los Angeles, California 90095
| | - Weerapan Khovidhunkit
- From the Department of Medicine, Faculty of Medicine, Chulalongkorn University and Thai Red Cross Society, Bangkok 10330, Thailand,
| | - André Bensadoun
- the Division of Nutritional Science, Cornell University, Ithaca, New York 14853
| | - Hirankorn Karnman
- From the Department of Medicine, Faculty of Medicine, Chulalongkorn University and Thai Red Cross Society, Bangkok 10330, Thailand
| | - Michael Ploug
- the Finsen Laboratory and Biotech Research and Innovation Center, Rigshospitalet, DK-2200 Copenhagen, Denmark
| | - Henrik Gårdsvoll
- the Finsen Laboratory and Biotech Research and Innovation Center, Rigshospitalet, DK-2200 Copenhagen, Denmark
| | | | | | - Mikael Larsson
- the Department of Medical Biosciences and Physiological Chemistry, Umeå University, SE-901 87 Umeå, Sweden, and
| | - Suwanna Muanpetch
- From the Department of Medicine, Faculty of Medicine, Chulalongkorn University and Thai Red Cross Society, Bangkok 10330, Thailand
| | - Supannika Charoen
- From the Department of Medicine, Faculty of Medicine, Chulalongkorn University and Thai Red Cross Society, Bangkok 10330, Thailand
| | | | - Sathit Niramitmahapanya
- the Department of Medicine, Rajavithi Hospital, College of Medicine, Rangsit University, Bangkok 10400, Thailand
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25
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Yamamoto H, Tanaka M, Yoshiga S, Funahashi T, Shimomura I, Kihara S. Autoimmune severe hypertriglyceridemia induced by anti-apolipoprotein C-II antibody. J Clin Endocrinol Metab 2014; 99:1525-30. [PMID: 24606081 DOI: 10.1210/jc.2013-3619] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Among type V hyperlipoproteinemias, only one-fourth of the patients have genetic defects in lipoprotein lipase (LPL) or in its associated molecules; the exact mechanism in other patients is usually unknown. OBJECTIVE The aim of the study was to report a case of severe hypertriglyceridemia induced by anti-apolipoprotein (apo) C-II autoantibody and to clarify its pathogenesis. SUBJECT AND METHODS A 29-year-old Japanese woman presented with severe persistent hypertriglyceridemia since the age of 20 years. The past history was negative for acute pancreatitis, eruptive xanthomas, or lipemia retinalis. LPL mass and activities were normal. Plasma apo C-II levels were extremely low, but no mutation was observed in APOC2. RESULTS Apo C-II protein was detected in the serum by immunoprecipitation and Western blotting. Large amounts of IgG and IgM were incorporated with apo C-II protein coimmunoprecipitated by anti-apo C-II antibody. IgG, but not IgM, purified from the serum prevented interaction of apo C-II with lipid substrate and diminished LPL hydrolysis activity. CONCLUSION We identified anti-apo C-II antibody in a myeloma-unrelated severe hypertriglyceridemic patient. In vitro analysis confirmed that the autoantibody disrupted the interaction between apo C-II and lipid substrate, suggesting the etiological role of anti-apo C-II antibody in severe hypertriglyceridemia in this patient.
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Affiliation(s)
- Hiroyasu Yamamoto
- Department of Biomedical Informatics, Division of Health Sciences (H.Y., M.T., S.Y., S.K.), and Department of Metabolic Medicine (T.F., I.S.), Osaka University Graduate School of Medicine, 565-0871 Osaka, Japan
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26
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Chokshi N, Blumenschein SD, Ahmad Z, Garg A. Genotype-phenotype relationships in patients with type I hyperlipoproteinemia. J Clin Lipidol 2014; 8:287-95. [PMID: 24793350 DOI: 10.1016/j.jacl.2014.02.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 01/07/2014] [Accepted: 02/12/2014] [Indexed: 12/17/2022]
Abstract
CONTEXT Type I hyperlipoproteinemia (T1HLP) is a rare, autosomal recessive disorder characterized by extreme hypertriglyceridemia that fails to respond to lipid-lowering agents, predisposing to frequent attacks of acute pancreatitis. Mutations in lipoprotein lipase (LPL), apolipoprotein CII (APOC2), lipase maturation factor 1 (LMF1), glycosyl-phosphatidylinositol anchored high-density lipoprotein-binding protein 1 (GPIHBP1), and apolipoprotein AV (APOA5) cause T1HLP, but we lack data on phenotypic variations among the different genetic subtypes. OBJECTIVE To study genotype-phenotype relationships among subtypes of T1HLP patients. DESIGN/INTERVENTION Genetic screening for mutations in LPL, APOC2, GPIHBP1, LMF1, and APOA5. SETTING Tertiary referral center. PATIENTS Ten patients (7 female, 3 male) with chylomicronemia, serum triglyceride levels about 2000 mg/dL, and no secondary causes of hypertriglyceridemia. MAIN OUTCOME MEASURES Genotyping and phenotypic features. RESULTS Four patients harbored homozygous or compound heterozygous mutations in LPL, 3 had homozygous mutations in GPIHBP1, and 1 had a heterozygous APOA5 mutation. We failed to fully identify the genetic etiology in 2 cases: 1 had a heterozygous LPL mutation only and another did not have any mutations. We identified 2 interesting phenotypic features: the patient with heterozygous APOA5 mutation normalized triglyceride levels with weight loss and fish oil therapy, and all 7 female patients were anemic. CONCLUSIONS Our data suggest the possibility of novel loci for T1HLP. We observed that heterozygous APOA5 mutation can cause T1HLP but such patients may unexpectedly respond to therapy, and females with T1HLP suffer from anemia. Further studies of larger cohorts may elucidate more phenotype-genotypes relationships among T1HLP subtypes.
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Affiliation(s)
- Neema Chokshi
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, Center for Human Nutrition
| | - Sarah D Blumenschein
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390
| | - Zahid Ahmad
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, Center for Human Nutrition
| | - Abhimanyu Garg
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, Center for Human Nutrition.
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27
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Affiliation(s)
- Federico Oldoni
- From the Departments of Molecular Genetics (F.O., J.A.K.) and Genetics (R.J.S.), University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Richard J. Sinke
- From the Departments of Molecular Genetics (F.O., J.A.K.) and Genetics (R.J.S.), University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Jan Albert Kuivenhoven
- From the Departments of Molecular Genetics (F.O., J.A.K.) and Genetics (R.J.S.), University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
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