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21/55. Familial chylomicronemia syndrome.

    Familial chylomicronemia syndrome is a group of rare genetic disorders characterized by deficient activity of an enzyme lipoprotein lipase or apo-protein C-II deficiency. incidence is 1 out of 1,000,000. Alternative names to this syndrome are Type I hyper lipoproteinemia and familial lipoprotein lipase deficiency.
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keywords = lipoprotein, deficiency
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22/55. Hyperchylomicronaemia due to lipoprotein lipase deficiency as a cause of false-positive newborn screening for biotinidase deficiency.

    Two cases of molecular genetically proven lipoprotein lipase deficiency are reported. Both patients were detected owing to a false-positive neonatal screening test for biotinidase deficiency. We conclude that both the fluorimetric and the colorimetric screening tests for biotinidase deficiency used with dried blood samples are affected by severe hyperchylomicronaemia and that, most probably, severe plasma turbidity interferes with the assay.
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ranking = 1.680566606352
keywords = lipoprotein, deficiency
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23/55. A missense mutation (Trp86

   Arg) in exon 3 of the lipoprotein lipase gene: a cause of familial chylomicronemia.     We have investigated a patient of English ancestry with familial chylomicronemia caused by lipoprotein lipase (LPL) deficiency. dna sequence analysis of all exons and intron-exon boundaries of the LPL gene identified two single-base mutations, a T   C transition for codon 86 (TGG) at nucleotide 511, resulting in a Trp86   Arg substitution, and a C   T transition at nucleotide 571, involving the codon CAG encoding Gln106 and producing Gln106   Stop, a mutation described by Emi et al. The functional significance of the two mutations was confirmed by in vitro expression and enzyme activity assays of the mutant LPL. Linkage analysis established that the patient is a compound heterozygote for the two mutations. The Trp86   Arg mutation in exon 3 is the first natural mutation identified outside exons 4-6, which encompass the catalytic triad residues.
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ranking = 1.6624362502407
keywords = lipoprotein, deficiency
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24/55. Missense mutation Leu72Pro located on the carboxyl terminal amphipathic helix of apolipoprotein c-ii causes familial chylomicronemia syndrome.

    BACKGROUND: Chylomicronemia syndrome can be caused by 2 autosomal recessive disorders - lipoprotein lipase (LPL) deficiency and apolipoprotein c-ii (apo C-II) deficiency. methods: We described 2 siblings with chylomicronemia syndrome of a consanguineous family. To determine the molecular basis of chylomicronemia syndrome in this family, we performed direct dna sequencing of the LPL and APOC2 genes of the proband. RESULTS: A novel homozygous mutation, Leu72Pro, in the APOC2 gene was found in both siblings whereas their parents were carriers. No LPL mutations were detected in the siblings. Apo C-II contains 3 amphipathic alpha helices; the C-terminal alpha helix is composed of residues 64 to 74. Substitution of residue 72 from a helix former leucine to a helix breaker, proline, is predicted to change the secondary structure of the C-terminal helix and subsequently alter the interaction between apo C-II and LPL. CONCLUSIONS: To our knowledge, Leu72Pro is the first missense mutation identified in the C-terminal of apo C-II. The result is consistent with the current biochemical and structural findings that the C-terminal helix of apo C-II is important for activation of LPL.
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ranking = 1.9963739287777
keywords = lipoprotein, deficiency
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25/55. Long-term course of lipoprotein lipase (LPL) deficiency due to homozygous LPL(Arita) in a patient with recurrent pancreatitis, retained glucose tolerance, and atherosclerosis.

    CONTEXT: lipoprotein lipase (LPL) deficiency is a rare autosomal recessive disorder caused by LPL gene mutation and is characterized by severe hyperchylomicronemia. patients with LPL deficiency suffer from the frequent recurrence of acute pancreatitis, but the underlying mechanisms are not fully understood. CASE REPORT: A 22-yr-old male Japanese patient with severe hyperchylomicronemia was admitted to our hospital in 1973. He had no consanguinity and no family history of hyperlipidemia. He was genetically diagnosed as LPL deficiency (homozygous for LPL(Arita)) with no LPL mass or activity in postheparin plasma. He has experienced recurrent acute pancreatitis 22 times during our 31-yr clinical follow-up, but no pancreatic pseudocyst, irregularity of the pancreatic duct, or abnormal pancreatic calcification was observed in computed tomography. Moreover, his pancreatic endocrine function, as assessed by the oral glucose tolerance test, has preserved more than 30 yr. Although he was a current smoker, no clinically significant atherosclerotic lesion had been observed. CONCLUSIONS: From the long-term observation of this patient, we propose that LPL deficiency is not invariably associated with high mortality and that even with repeated episodes of acute pancreatitis, pancreatic function may be slow to decline.
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ranking = 1.3430028565927
keywords = lipoprotein, deficiency
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26/55. A novel substitution at the translation initiator codon (ATG-->ATC) of the lipoprotein lipase gene is mainly responsible for lipoprotein lipase deficiency in a patient with severe hypertriglyceridemia and recurrent pancreatitis.

    A patient with severe hypertriglyceridemia and recurrent pancreatitis was found to have significantly decreased lipoprotein lipase (LPL) activity and normal apolipoprotein c-ii concentration in post-heparin plasma. dna analysis of the LPL gene revealed two mutations, one of which was a novel homozygous G-->C substitution, resulting in the conversion of a translation initiation codon methionine to isoleucine (LPL-1). The second was the previously reported heterozygous substitution of glutamic acid at residue 242 with lysine (LPL-242). in vitro expression of both mutations separately or in combination demonstrated that LPL-1 had approximately 3% protein mass and 2% activity, whereas LPL-242 had undetectable activity but normal mass. The combined mutation LPL-1-242 exhibited similar changes as for LPL-1, with markedly reduced mass, and for LPL-242, with undetectable activity. These results suggest that the homozygous initiator codon mutation rather than the heterozygous LPL-242 alteration was mainly responsible for the patient phenotypes.
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ranking = 3.3284985717036
keywords = lipoprotein, deficiency
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27/55. Identification of two separate allelic mutations in the lipoprotein lipase gene of a patient with the familial hyperchylomicronemia syndrome.

    The molecular defects resulting in a deficiency of lipoprotein lipase activity in a patient with the familial hyperchylomicronemia syndrome have been identified. Increased lipoprotein lipase mass but undetectable lipoprotein lipase activity in the patient's post-heparin plasma indicate the presence of an inactive enzyme. No major gene rearrangements were identified by Southern blot analysis of the patient's lipoprotein lipase gene and Northern blot hybridization revealed an lipoprotein lipase mRNA of normal size. sequence analysis of polymerase chain reaction-amplified lipoprotein lipase cDNA identified two separate allelic mutations. A T to C transition at nucleotide 836 results in the substitution of Ile194, located near the putative interfacial recognition site of lipoprotein lipase, to a Thr. A G to A mutation at base 983 leads to the substitution of a His for Arg243 and the loss of a HhaI restriction enzyme site. Arg243 is near His241, which has been postulated to be part of the catalytic triad of lipoprotein lipase. Direct sequencing of amplified cDNA and digestion with HhaI established that the proband is a compound heterozygote for each base substitution. Transient expression of each of the mutant lipoprotein lipase cDNAs in human embryonal kidney-293 cells resulted in the synthesis of enzymically inactive proteins, establishing the functional significance of the mutations. We conclude that the Ile194 to Thr194 and Arg243 to His243 substitutions occur in lipoprotein lipase regions essential for normal enzyme activity and each mutation results in the expression of a nonfunctional enzyme leading to the hyperchylomicronemia syndrome manifested in the proband.
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ranking = 4.6515580365739
keywords = lipoprotein, deficiency
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28/55. hyperlipoproteinemia type i in a patient with active lipoprotein lipase in adipose tissue and indications of defective transport of the enzyme.

    This paper presents a case of typical hyperlipoproteinemia type i in a young woman. Her serum triglycerides varied between 2 and 90 mmol/l and she had substantial amounts of apolipoprotein b-48 in fasting plasma. She had no detectable lipoprotein lipase (LPL) activity in post-heparin plasma (less than 0.2 percent of normal). Southern blot analysis suggested no major defect in her LPL gene and Northern blot analysis of adipose tissue rna showed normal-sized LPL-mRNA. A 2-h [35S]methionine incorporation experiment with adipose tissue pieces in vitro showed that she produced normal-sized LPL and had LPL catalytic activity in the tissue. The amounts were, however, only 5-10% of control. No detectable LPL radioactivity or catalytic activity was released from patient tissue even in the presence of heparin in the incubations. Immunofluorescent staining of adipose tissue biopsies from the patient showed LPL immunoreactivity only in adipocytes and little or none within the capillaries. Treatment of immunoprecipitated labeled LPL with endoglycosidase H showed that the oligosaccharide chains on her enzyme were of the high-mannose type and not processed as in controls. Taken together the data suggest that the patient synthesizes a relatively normal LPL protein which is core-glycosylated and folded into active enzyme as in normal subjects, but is not effectively transported via the Golgi to the cell surface.
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ranking = 3.653371072185
keywords = lipoprotein
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29/55. Familial type I hyperlipoproteinemia caused by apolipoprotein c-ii deficiency.

    A study was made on the clinical and biochemical features of siblings of patients with hyperchylomicronemia and its inherited relationship. It was not a case of the classical type of familial LPL deficiency, but of familial apolipoprotein c-ii deficiency. The first patient with apolipoprotein c-ii deficiency was reported by Breckenridge et al. and our patients provide the basis for the second report of this new disease. Our observations in this study strongly suggest that familial apolipoprotein c-ii deficiency is transmitted by an autosomal recessive mode of inheritance and heterozygotes of this disorder have no abnormalities of plasma lipid and lipoproteins in spite of the reduced plasma apolipoprotein c-ii.
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ranking = 4.3321246429259
keywords = lipoprotein, deficiency
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30/55. lipoprotein lipase deficiency resulting from a nonsense mutation in exon 3 of the lipoprotein lipase gene.

    In dna from a male patient of German and Polish ancestry who has lipoprotein lipase deficiency, sequencing of all nine exons and intron-exon boundaries corresponding to the coding region of the lipoprotein lipase gene detected a C   T transition leading to the substitution of a stop signal for the codon that normally determines a glutamine at position 106 of the mature enzyme. Hybridization with allele-specific oligonucleotides at this position established that the patient was homozygous for this mutation. This mutation must lead to the synthesis of a sharply truncated protein, accounting for the enzymatic deficiency noted in the patient.
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ranking = 2.0036260712223
keywords = lipoprotein, deficiency
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