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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 -
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 -
JCI Insight Jul 2021Apolipoprotein B (ApoB) is the primary protein of chylomicrons, VLDLs, and LDLs and is essential for their production. Defects in ApoB synthesis and secretion result in...
Apolipoprotein B (ApoB) is the primary protein of chylomicrons, VLDLs, and LDLs and is essential for their production. Defects in ApoB synthesis and secretion result in several human diseases, including abetalipoproteinemia and familial hypobetalipoproteinemia (FHBL1). In addition, ApoB-related dyslipidemia is linked to nonalcoholic fatty liver disease (NAFLD), a silent pandemic affecting billions globally. Due to the crucial role of APOB in supplying nutrients to the developing embryo, ApoB deletion in mammals is embryonic lethal. Thus, a clear understanding of the roles of this protein during development is lacking. Here, we established zebrafish mutants for 2 apoB genes: apoBa and apoBb.1. Double-mutant embryos displayed hepatic steatosis, a common hallmark of FHBL1 and NAFLD, as well as abnormal liver laterality, decreased numbers of goblet cells in the gut, and impaired angiogenesis. We further used these mutants to identify the domains within ApoB responsible for its functions. By assessing the ability of different truncated forms of human APOB to rescue the mutant phenotypes, we demonstrate the benefits of this model for prospective therapeutic screens. Overall, these zebrafish models uncover what are likely previously undescribed functions of ApoB in organ development and morphogenesis and shed light on the mechanisms underlying hypolipidemia-related diseases.
Topics: Animals; Apolipoproteins B; Embryonic Development; Endothelial Cells; Fatty Liver; Goblet Cells; Intestines; Models, Biological; Mutation; Neovascularization, Pathologic; Vascular Remodeling; Zebrafish; Zebrafish Proteins
PubMed: 34236046
DOI: 10.1172/jci.insight.130399 -
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 -
Journal of Investigative Medicine High... 2021Abetalipoproteinemia (ABL) is a rare recessive condition caused by biallelic loss-of-function mutations in the gene encoding the microsomal triglyceride transfer...
Abetalipoproteinemia (ABL) is a rare recessive condition caused by biallelic loss-of-function mutations in the gene encoding the microsomal triglyceride transfer protein large subunit. ABL is characterized by absence of apolipoprotein B-containing lipoproteins and deficiencies in fat-soluble vitamins leading to multisystem involvement of which neurological complications are the most serious. We present 3 siblings with ABL who were born to non-consanguineous parents of Filipino and Chinese background. Identical twin boys with long-standing failure to thrive and malabsorption were diagnosed at age 2 years. ABL therapy with vitamins and a specialized diet was initiated, replacing total parenteral nutrition at age 3 years. Their younger sister was diagnosed from a blood sample taken at birth; treatment was instituted shortly thereafter. We observed in the twins reversal and in their sister prevention of ABL systemic features following early implementation of fat restriction and high doses of oral fat-soluble vitamins. A targeted sequencing panel found that each affected sibling is homozygous for a novel intron 13 -2A>G splice acceptor site mutation, predicted to abolish splicing of intron 13. This variant brings to more than 60 the number of reported pathogenic mutations, which are summarized in this article. The twin boys and their sister are now doing well at 11 and 4 years of age, respectively. This experience underscores the importance of early initiation of targeted specialized dietary and fat-soluble vitamin replacements in ABL.
Topics: Abetalipoproteinemia; Child, Preschool; Humans; Infant, Newborn; Male; Mutation; Siblings; Thymine Nucleotides; Vitamin A
PubMed: 34078172
DOI: 10.1177/23247096211022484 -
Journal of Atherosclerosis and... Oct 2021Abetalipoproteinemia (ABL) is a rare autosomal recessive disorder caused by biallelic pathogenic mutations in the MTTP gene. Deficiency of microsomal triglyceride... (Review)
Review
Abetalipoproteinemia (ABL) is a rare autosomal recessive disorder caused by biallelic pathogenic mutations in the MTTP gene. Deficiency of microsomal triglyceride transfer protein (MTTP) abrogates the assembly of apolipoprotein (apo) B-containing lipoprotein in the intestine and liver, resulting in malabsorption of fat and fat-soluble vitamins and severe hypolipidemia. Patients with ABL typically manifest steatorrhea, vomiting, and failure to thrive in infancy. The deficiency of fat-soluble vitamins progressively develops into a variety of symptoms later in life, including hematological (acanthocytosis, anemia, bleeding tendency, etc.), neuromuscular (spinocerebellar ataxia, peripheral neuropathy, myopathy, etc.), and ophthalmological symptoms (e.g., retinitis pigmentosa). If left untreated, the disease can be debilitating and even lethal by the third decade of life due to the development of severe complications, such as blindness, neuromyopathy, and respiratory failure. High dose vitamin supplementation is the mainstay for treatment and may prevent, delay, or alleviate the complications and improve the prognosis, enabling some patients to live to the eighth decade of life. However, it cannot fully prevent or restore impaired function. Novel therapeutic modalities that improve quality of life and prognosis are awaited. The aim of this review is to 1) summarize the pathogenesis, clinical signs and symptoms, diagnosis, and management of ABL, and 2) propose diagnostic criteria that define eligibility to receive financial support from the Japanese government for patients with ABL as a rare and intractable disease. In addition, our diagnostic criteria and the entry criterion of low-density lipoprotein cholesterol (LDL-C) <15 mg/dL and apoB <15 mg/dL can be useful in universal or opportunistic screening for the disease. Registry research on ABL is currently ongoing to better understand the disease burden and unmet needs of this life-threatening disease with few therapeutic options.
Topics: Abetalipoproteinemia; Apolipoproteins B; Cholesterol, LDL; Cost of Illness; Disease Management; Humans; Prognosis
PubMed: 33994405
DOI: 10.5551/jat.RV17056 -
JPGN Reports Feb 2021Supplemental Digital Content is available in the text.
Supplemental Digital Content is available in the text.
PubMed: 37206948
DOI: 10.1097/PG9.0000000000000049 -
Journal of Clinical Laboratory Analysis Mar 2021Our aims were to describe the first Mexican patient with abetalipoproteinemia and to perform a comparative analysis of biochemical, clinical, and genetic characteristics...
A novel p.Gly417Valfs*12 mutation in the MTTP gene causing abetalipoproteinemia: Presentation of the first patient in Mexico and analysis of the previously reported cases.
BACKGROUND
Our aims were to describe the first Mexican patient with abetalipoproteinemia and to perform a comparative analysis of biochemical, clinical, and genetic characteristics of 100 cases reported in the literature.
METHODS
We performed biochemical and molecular screenings in a Mexican girl with extremely low lipid levels and in her family. Further, we integrated and evaluated the characteristics of the cases with abetalipoproteinemia described in the literature.
RESULTS
Our patient is a six-year-old girl who presented vomiting, chronic diarrhea, failure to thrive, malabsorption, acanthocytosis, anemia, transaminases elevation, and extremely low lipid levels. MTTP gene sequencing revealed homozygosity for a novel mutation p.Gly417Valfs*12 (G deletion c.1250). With the analysis of the reported cases, 60 clinical features (14 classical and 46 non-classical) were observed, being the most common acanthocytosis (57.5%), malabsorption (43.7%), and diarrhea (42.5%); 48.8% of the patients presented only classic clinical features, while the remaining 51.2% developed secondary effects due to a fat-soluble vitamin deficiency. An odds ratio analysis disclosed that patients diagnosed after 10 years of age have an increased risk for presenting clinical complications (OR = 18.0; 95% CI 6.0-54.1, p < 0.0001). A great diversity of mutations in MTTP has been observed (n = 76, being the most common p.G865X and p.N139_E140) and some of them with possible residual activity.
CONCLUSION
The first Mexican patient with abetalipoproteinemia presents a novel MTTP mutation p.Gly417Valfs*12. Three factors that could modulate the phenotype in abetalipoproteinemia were identified: age at diagnosis, treatment, and the causal mutation.
Topics: Abetalipoproteinemia; Adolescent; Adult; Carrier Proteins; Child; Female; Humans; Male; Mexico; Middle Aged; Mutation; Pedigree
PubMed: 33258201
DOI: 10.1002/jcla.23672 -
Arteriosclerosis, Thrombosis, and... Sep 2020Dyslipidemias include both rare single gene disorders and common conditions that have a complex underlying basis. In London, ON, there is fortuitous close physical...
Dyslipidemias include both rare single gene disorders and common conditions that have a complex underlying basis. In London, ON, there is fortuitous close physical proximity between the Lipid Genetics Clinic and the London Regional Genomics Centre. For >30 years, we have applied DNA sequencing of clinical samples to help answer scientific questions. More than 2000 patients referred with dyslipidemias have participated in an ongoing translational research program. In 2013, we transitioned to next-generation sequencing; our targeted panel is designed to concurrently assess both monogenic and polygenic contributions to dyslipidemias. Patient DNA is screened for rare variants underlying 25 mendelian dyslipidemias, including familial hypercholesterolemia, hepatic lipase deficiency, abetalipoproteinemia, and familial chylomicronemia syndrome. Furthermore, polygenic scores for LDL (low-density lipoprotein) and HDL (high-density lipoprotein) cholesterol, and triglycerides are calculated for each patient. We thus simultaneously document both rare and common genetic variants, allowing for a broad view of genetic predisposition for both individual patients and cohorts. For instance, among patients referred with severe hypertriglyceridemia, defined as ≥10 mmol/L (≥885 mg/dL), <1% have a mendelian disorder (ie, autosomal recessive familial chylomicronemia syndrome), ≈15% have heterozygous rare variants (a >3-fold increase over normolipidemic individuals), and ≈35% have an extreme polygenic score (a >3-fold increase over normolipidemic individuals). Other dyslipidemias show a different mix of genetic determinants. Genetic results are discussed with patients and can support clinical decision-making. Integrating DNA testing into clinical care allows for a bidirectional flow of information, which facilitates scientific discoveries and clinical translation.
Topics: Biomarkers; DNA Copy Number Variations; Dyslipidemias; Genetic Predisposition to Disease; Genetic Testing; Genetic Variation; High-Throughput Nucleotide Sequencing; History, 20th Century; History, 21st Century; Humans; Lipids; Multifactorial Inheritance; Phenotype; Prognosis; Risk Assessment; Risk Factors
PubMed: 32762461
DOI: 10.1161/ATVBAHA.120.313065 -
Annals of Indian Academy of Neurology 2020Movement disorders in childhood comprise a heterogeneous group of conditions that lead to impairment of voluntary movement, abnormal postures, or inserted involuntary...
Movement disorders in childhood comprise a heterogeneous group of conditions that lead to impairment of voluntary movement, abnormal postures, or inserted involuntary movements. Movement disorders in children are frequently caused by metabolic disorders, both inherited and acquired. Many of these respond to vitamin supplementation. Examples include infantile tremor syndrome, biotinidase deficiency, biotin-thiamine-responsive basal ganglia disease, pyruvate dehydrogenase deficiency, aromatic amino acid decarboxylase deficiency, ataxia with vitamin E deficiency, abetalipoproteinemia, cerebral folate deficiency, and cobalamin metabolism defects. Recognition of these disorders by pediatricians and neurologists is imperative as they are easily treated by vitamin supplementation. In this review, we discuss vitamin-responsive movement disorders in children.
PubMed: 32606520
DOI: 10.4103/aian.AIAN_678_19