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Journal of Clinical Lipidology 2022Complete deficiency of apolipoprotein (apo) B-containing lipoproteins can result from both abetalipoproteinemia (ABL) and homozygous hypobetalipoproteinemia (HoHBL),...
Complete deficiency of apolipoprotein (apo) B-containing lipoproteins can result from both abetalipoproteinemia (ABL) and homozygous hypobetalipoproteinemia (HoHBL), caused by bi-allelic loss-of-function variants in the MTTP and APOB genes encoding microsomal triglyceride transfer protein and apolipoprotein (apo) B, respectively. Both conditions are associated with failure to assemble and secrete apo B-containing lipoproteins from intestine and liver, resulting in absence of chylomicrons, very low-density lipoproteins and remnants, and low-density lipoproteins. Because absorption and transport of fat soluble vitamins requires intact production of apo B-containing lipoproteins, untreated patients develop fat soluble vitamin deficiencies, with associated clinical features including atypical retinitis pigmentosa, osteopenia, neuromyopathy and coagulopathy. Other features include acanthocytosis on the peripheral blood film, fat malabsorption and hepatosteatosis. We describe two patients with ABL and one with HoHBL who have each been on high dose oral fat soluble vitamin replacement under the care of the same physician for more than four decades. Each patient has remained clinically stable. A recent liver biopsy from an ABL patient showed mild macrovesicular steatosis, patchy microvesicular steatosis and mild fibrosis. These observations add to our understanding of the long term trajectory of ABL and HoHBL, and emphasize the importance of compliance to treatment and follow up.
Topics: Abetalipoproteinemia; Apolipoprotein B-100; Apolipoproteins B; Follow-Up Studies; Humans; Hypobetalipoproteinemias; Lipoproteins; Lipoproteins, LDL
PubMed: 35221233
DOI: 10.1016/j.jacl.2022.02.003 -
JPGN Reports Nov 2022Cow's milk protein allergy (CMPA) is an abnormal immunologic response to bovine protein that can result in various gastrointestinal and cutaneous manifestations...
Cow's milk protein allergy (CMPA) is an abnormal immunologic response to bovine protein that can result in various gastrointestinal and cutaneous manifestations including diarrhea, failure to thrive, malabsorption, and even protein-losing enteropathy. We describe a case of a 7-month-old breastfed male who presented with severe atopic dermatitis, emesis, oily diarrhea, failure to thrive, electrolyte disturbance, and hemodynamic instability. Following stabilization, additional evaluation revealed concern for abetalipoproteinemia. Ultimately, the patient's symptoms resolved with introduction of an elemental formula and returned with reinitiation of cow's milk protein, confirming the diagnosis of severe CMPA. It is important for the general practitioner to be aware of the various presentations and have a high index of suspicion for CMPA as no symptom or diagnostic test is pathognomonic for diagnosis. Even though it can mimic other causes of malabsorption, a trial with extensively hydrolyzed or elemental formula should be attempted before undertaking invasive testing.
PubMed: 37168480
DOI: 10.1097/PG9.0000000000000246 -
Journal of Atherosclerosis and... Jun 2022Primary dyslipidemias are inherited disorders in plasma lipoprotein metabolism that lead to serious cardiovascular and other complications. The Japanese Ministry of...
INTRODUCTION
Primary dyslipidemias are inherited disorders in plasma lipoprotein metabolism that lead to serious cardiovascular and other complications. The Japanese Ministry of Health, Labor and Welfare (MHLW) covers medical expenses, under the Research Program on Rare and Intractable Diseases, for homozygous familial hypercholesterolemia (FH), familial chylomicronemia, sitosterolemia, cerebrotendinous xanthomatosis, lecithin:cholesterol acyltransferase deficiency, Tangier disease, and abetalipoproteinemia. Apolipoprotein A1 deficiency, heterozygous FH, and type III hyperlipoproteinemia are covered by the MHLW Pediatric Chronic Disease Program. Heterozygous FH and type III hyperlipoproteinemia are also important for their relatively common prevalence and, accordingly, high impact on Japanese public health by significant contribution to the overall prevalence of cardiovascular diseases. Therefore, a systemic survey of these diseases is mandatory to estimate their actual situation, such as prevalence, clinical manifestations, and prognoses among the Japanese population. The impact of these rare and intractable diseases on cardiovascular and other complications will likely be higher among Japanese people than other ethnicities because the general Japanese population has many cardioprotective aspects. The current study intends to conduct a multicenter registry of these diseases to assess their demographics and clinical features comprehensively.
METHODS AND ANALYSIS
The Prospective Registry Study of Primary Dyslipidemia is a registry-based prospective, observational, multicenter cohort study in Japan, enrolling patients who fulfill the Japanese clinical criteria of the primary dyslipidemias listed above, from 26 participating institutes from August 2015 to March 2023. A total of 1,000 patients will be enrolled in the study and followed for 10 years. Clinical parameters are collected, including physical and laboratory findings, genetic analysis, drugs, lifestyle management, and clinical events, especially cardiovascular events. The primary endpoint of this study is the new onset of cardiovascular disease and acute pancreatitis, and the secondary endpoint is death from any causes.
ETHICS AND DISSEMINATION
This study complies with the Declaration of Helsinki, the Ethical Guidelines for Medical and Health Research Involving Human Subjects, and all other applicable laws and guidelines in Japan. The institutional review boards have approved this study protocol at all participating institutes. The final results are to be published at appropriate international conferences and in peer-reviewed journals.
Topics: Acute Disease; Cardiovascular Diseases; Child; Cohort Studies; Dyslipidemias; Humans; Hyperlipoproteinemia Type II; Hyperlipoproteinemia Type III; Pancreatitis; Registries
PubMed: 34690220
DOI: 10.5551/jat.63222 -
Advances in Experimental Medicine and... 2022Sphingolipids are biomolecules with diverse physiological functions in signaling as well as plasma membrane structure. They are associated with either cellular membranes...
Sphingolipids are biomolecules with diverse physiological functions in signaling as well as plasma membrane structure. They are associated with either cellular membranes or plasma lipoproteins and any changes in their levels may contribute to certain metabolic diseases. Sphingolipids are evenly distributed in lipoproteins and may be used as prognostic and diagnostic markers. Mechanisms involved in the transport of sphingolipids have been recently explored and here we discuss the most recent advances in the molecular mechanisms of sphingolipids transport by lipoproteins. It has been shown that microsomal triglyceride transfer protein (MTP) and ATP-binding cassette transporter family A protein 1 (ABCA1) play an important role in plasma sphingolipid homeostasis. However, the exact mechanisms are not well known. Though much research has already been done to emphasize the impact of sphingolipids changes in many pathological disorders, understanding mechanisms by which circulating lipoproteins assist in transporting sphingolipids may provide novel information that may help in devising strategies to therapeutically target these pathways to treat various metabolic disorders.
Topics: Ceramides; Homeostasis; Humans; Lipoproteins; Metabolic Diseases; Sphingolipids
PubMed: 35503174
DOI: 10.1007/978-981-19-0394-6_5 -
Journal of Lipid Research Sep 2022The microsomal triglyceride transfer protein (MTP) is essential for the secretion of apolipoprotein B (apoB)48- and apoB100-containing lipoproteins in the intestine and...
The microsomal triglyceride transfer protein (MTP) is essential for the secretion of apolipoprotein B (apoB)48- and apoB100-containing lipoproteins in the intestine and liver, respectively. Loss of function mutations in MTP cause abetalipoproteinemia. Heterologous cells are used to evaluate the function of MTP in apoB secretion to avoid background MTP activity in liver and intestine-derived cells. However, these systems are not suitable to study the role of MTP in the secretion of apoB100-containing lipoproteins, as expression of a large apoB100 peptide using plasmids is difficult. Here, we report a new cell culture model amenable for studying the role of different MTP mutations on apoB100 secretion. The endogenous MTTP gene was ablated in human hepatoma Huh-7 cells using single guide RNA and RNA-guided clustered regularly interspaced short palindromic repeats-associated sequence 9 ribonucleoprotein complexes. We successfully established three different clones that did not express any detectable MTTP mRNA or MTP protein or activity. These cells were defective in secreting apoB-containing lipoproteins and accumulated lipids. Furthermore, we show that transfection of these cells with plasmids expressing human MTTP cDNA resulted in the expression of MTP protein, restoration of triglyceride transfer activity, and secretion of apoB100. Thus, these new cells can be valuable tools for studying structure-function of MTP, roles of different missense mutations in various lipid transfer activities of MTP, and their ability to support apoB100 secretion, compensatory changes associated with loss of MTP, and in the identification of novel proteins that may require MTP for their synthesis and secretion.
Topics: Apolipoprotein B-48; Apolipoproteins B; Carcinoma, Hepatocellular; Carrier Proteins; Cell Line; DNA, Complementary; Humans; Lipoproteins; Liver Neoplasms; RNA, Guide, CRISPR-Cas Systems; RNA, Messenger; Ribonucleoproteins; Triglycerides
PubMed: 35931202
DOI: 10.1016/j.jlr.2022.100257 -
Journal of Atherosclerosis and... May 2024Familial hypobetalipoproteinemia (FHBL) 1 is a rare genetic disorder with an autosomal codominant mode of inheritance and is caused by defects in the apolipoprotein...
Familial hypobetalipoproteinemia (FHBL) 1 is a rare genetic disorder with an autosomal codominant mode of inheritance and is caused by defects in the apolipoprotein (apo) B (APOB) gene that disable lipoprotein formation. ApoB proteins are required for the formation of very low-density lipoproteins (VLDLs), chylomicrons, and their metabolites. VLDLs transport cholesterol and triglycerides from the liver to the peripheral tissues, whereas chylomicrons transport absorbed lipids and fat-soluble vitamins from the intestine. Homozygous or compound heterozygotes of FHBL1 (HoFHBL1) are extremely rare, and defects in APOB impair VLDL and chylomicron secretion, which result in marked hypolipidemia with malabsorption of fat and fat-soluble vitamins, leading to various complications such as growth disorders, acanthocytosis, retinitis pigmentosa, and neuropathy. Heterozygotes of FHBL1 are relatively common and are generally asymptomatic, except for moderate hypolipidemia and possible hepatic steatosis. If left untreated, HoFHBL1 can cause severe complications and disabilities that are pathologically and phenotypically similar to abetalipoproteinemia (ABL) (an autosomal recessive disorder) caused by mutations in the microsomal triglyceride transfer protein (MTTP) gene. Although HoFHBL1 and ABL cannot be distinguished from the clinical manifestations and laboratory findings of the proband, moderate hypolipidemia in first-degree relatives may help diagnose HoFHBL1. There is currently no specific treatment for HoFHBL1. Palliative therapy including high-dose fat-soluble vitamin supplementation may prevent or delay complications. Registry research on HoFHBL1 is currently ongoing to better understand the disease burden and unmet needs of this life-threatening disease with few therapeutic options.
PubMed: 38710625
DOI: 10.5551/jat.RV22018 -
Journal of Ayub Medical College,... 2023Klipple-Trenaunay syndrome (KTS) is an extremely rare congenital vascular disorder with poorly defined incidence and prevalence. We report a case of a patient who...
Klipple-Trenaunay syndrome (KTS) is an extremely rare congenital vascular disorder with poorly defined incidence and prevalence. We report a case of a patient who presented after road traffic accident with primary complaints of poor wound healing and persistent bleeding from wound site. Discernible presence of arteriovenous malformation and skin hypertrophy since birth lead to the diagnosis of Klipple-Trenaunay syndrome (KTS). There was an incidental finding of acanthocytosis on peripheral film of blood which remained elevated even after clinical improvement of the patient. This case report highlights a close association of marked acanthocytosis of red blood cells and Klipple-Trenaunay syndrome.
Topics: Humans; Abetalipoproteinemia; Erythrocytes
PubMed: 36849406
DOI: 10.55519/JAMC-01-11307 -
Journal of Pediatric Gastroenterology... Jul 2021Familial intestinal hypocholesterolemias, such as abetalipoproteinemia, hypobetalipoproteinemia, and chylomicron retention disease, are rare genetic diseases that result...
Familial intestinal hypocholesterolemias, such as abetalipoproteinemia, hypobetalipoproteinemia, and chylomicron retention disease, are rare genetic diseases that result in a defect in the synthesis or secretion of lipoproteins containing apolipoprotein B.In children, these conditions present with diarrhoea and growth failure, whereas adults present with neuromuscular, ophthalmological, and hepatic symptoms. Simple laboratory investigations have shown that diagnosis can be made from findings of dramatically decreased cholesterol levels, deficiencies in fat-soluble vitamins (mostly vitamin E), endoscopic findings of the characteristic white intestinal mucosa, and fat-loaded enterocytes in biopsy samples. Genetic analysis is used to confirm the diagnosis. Treatment is based on a low-fat diet with essential fatty acid supplementation, high doses of fat-soluble vitamins, and regular and life-long follow-up.The present study examines cases and literature findings of these conditions, and emphasises the need to explore severe hypocholesterolemia and deficiencies in fat-soluble vitamins to not miss these rare, but easy to diagnose and treat, disorders.
Topics: Abetalipoproteinemia; Adult; Apolipoproteins B; Child; Humans; Hypobetalipoproteinemias; Lipids; Vitamin E
PubMed: 33853111
DOI: 10.1097/MPG.0000000000003145 -
Nutrients Jan 2023Abetalipoproteinemia (FHBL-SD1) and chylomicron retention disease (FHBL-SD3) are rare recessive disorders of lipoprotein metabolism due to mutations in and genes,...
Abetalipoproteinemia (FHBL-SD1) and chylomicron retention disease (FHBL-SD3) are rare recessive disorders of lipoprotein metabolism due to mutations in and genes, respectively, which lead to defective chylomicron formation and secretion. This results in lipid and fat-soluble vitamin malabsorption, which induces severe neuro-ophthalmic complications. Currently, treatment combines a low-fat diet with high-dose vitamin A and E supplementation but still fails in normalizing serum vitamin E levels and providing complete ophthalmic protection. To explore these persistent complications, we developed two knock-out cell models of FHBL-SD1 and FHBL-SD3 using the CRISPR/Cas9 technique in Caco-2/TC7 cells. DNA sequencing, RNA quantification and Western blotting confirmed the introduction of mutations with protein knock-out in four clones associated with i) impaired lipid droplet formation and ii) defective triglyceride (-57.0 ± 2.6% to -83.9 ± 1.6%) and cholesterol (-35.3 ± 4.4% to -60.6 ± 3.5%) secretion. A significant decrease in α-tocopherol secretion was also observed in these clones (-41.5 ± 3.7% to -97.2 ± 2.8%), even with the pharmaceutical forms of vitamin E: tocopherol-acetate and tocofersolan (α-tocopheryl polyethylene glycol succinate 1000). silencing led to a more severe phenotype than silencing, which is consistent with clinical observations. Our cellular models thus provide an efficient tool to experiment with therapeutic strategies and will allow progress in understanding the mechanisms involved in lipid metabolism.
Topics: Humans; alpha-Tocopherol; Apolipoproteins B; Caco-2 Cells; Enterocytes; Hypobetalipoproteinemias; Monomeric GTP-Binding Proteins; Vitamin E
PubMed: 36771214
DOI: 10.3390/nu15030505 -
Cells Jun 2021Human microsomal triglyceride transfer protein (hMTP) plays an essential role in the assembly of apoB-containing lipoproteins, and has become an important drug target...
Human microsomal triglyceride transfer protein (hMTP) plays an essential role in the assembly of apoB-containing lipoproteins, and has become an important drug target for the treatment of several disease states, such as abetalipoproteinemia, fat malabsorption and familial hypercholesterolemia. hMTP is a heterodimer composed of a larger hMTPα subunit and a smaller hMTPβ subunit (namely, protein disulfide isomerase, hPDI). hPDI can interact with 17β-estradiol (E), an endogenous female sex hormone. It has been reported that E can significantly reduce the blood levels of low-density lipoprotein, cholesterol and triglyceride, and modulate liver lipid metabolism in vivo. However, some of the estrogen's actions on lipid metabolism are not associated with estrogen receptors (ER), and the exact mechanism underlying estrogen's ER-independent lipid-modulating action is still not clear at present. In this study, the potential influence of E on the stability of the hMTP complex is investigated by jointly using multiple molecular dynamics analyses based on available experimental structures. The molecular dynamics analyses indicate that the hMTP complex in the presence of E has reduced interface contacts and surface areas. A steered molecular dynamics analysis shows that the forces required to separate the two subunits (namely, hPDI and hMTPα subunit) of the hMTP complex in the absence of E are significantly higher than the forces required to separate the complex in which its hPDI is already bound with E. E makes the interface between hMTPα and hPDI subunits more flexible and less stable. The results of this study suggest that E-induced conformational changes of the hMTP complex might be a novel mechanism partly accounting for the ER-independent lipid-modulating effect of E.
Topics: Carrier Proteins; Estradiol; Humans; Molecular Dynamics Simulation; Protein Conformation; Protein Subunits; Thermodynamics
PubMed: 34206252
DOI: 10.3390/cells10071566