Hyperlipidemias: Schmidt H

Dedoussis GV, Schmidt H, Genschel J. · Department of Science Dietetics-Nutrition, Harokopio University of Athens, Athens, Greece. · Hum Mutat. · Pubmed #15523646 No free full text.

Abstract: Familial hypercholesterolemia (FH) is a clinical definition for a remarkable increase of cholesterol serum concentration, presence of xanthomas, and an autosomal dominant trait of either increased serum cholesterol or premature coronary artery disease (CAD). The identification of the low-density lipoprotein (LDL)-receptor (LDLR) as the underlying cause and its genetic characterization in FH patients revealed more insights in the trafficking of LDL, which primarily transports cholesterol to hepatic and peripheral cells. Mutations within LDLR result in hypercholesterolemia and, subsequently, cholesterol deposition in humans to a variable degree. This confirms the pathogenetic role of LDLR and also highlights the existence of additional factors in determining the phenotype. Autosomal dominant FH is caused by LDLR deficiency and defective apolipoprotein B-100 (APOB), respectively. Heterozygosity of the LDLR is relatively common (1:500). Clinical diagnosis is highly important and genetic diagnosis may be helpful, since treatment is usually effective for this otherwise fatal disease. Very recently, mutations in PCSK9 have been also shown to cause autosomal dominant hypercholesterolemia. For autosomal recessive hypercholesterolemia, mutations within the so-called ARH gene encoding a cellular adaptor protein required for LDL transport have been identified. These insights emphasize the crucial importance of LDL metabolism intra- and extracellularly in determining LDL-cholesterol serum concentration. Herein, we focus on the published European LDLR mutation data that reflect its heterogeneity and phenotypic penetrance.

Enzinger C, Fazekas F, Matthews PM, Ropele S, Schmidt H, Smith S, Schmidt R. · Department of Neurology, Medical University Graz, Graz, Austria. · Neurology. · Pubmed #15911795 No free full text.

Abstract: OBJECTIVES: To determine the rate of brain atrophy in neurologically asymptomatic elderly and to investigate the impact of baseline variables including conventional cerebrovascular risk factors, APOE epsilon4, and white matter hyperintensity (WMH) on its progression. METHODS: We assessed the brain parenchymal fraction at baseline and subsequent annual brain volume changes over 6 years for 201 participants (F/M = 96/105; 59.8 +/- 5.9 years) in the Austrian Stroke Prevention Study from 1.5-T MRI scans using SIENA (structural image evaluation using normalization of atrophy)/SIENAX (an adaptation of SIENA for cross-sectional measurement)(www.fmrib.ox.ac.uk/fsl). Hypertension, cardiac disease, diabetes mellitus, smoking, and regular alcohol intake were present in 64 (31.8%), 60 (29.9%), 5 (2.5%), 70 (39.3%), and 40 (20.7%) subjects, respectively. Plasma levels of fasting glucose (93.7 +/- 18.6 mg/dL), glycated hemoglobin A (HbA1c; 5.6 +/- 0.7%), total cholesterol (228.3 +/- 40.3 mg/dL), and triglycerides (127.0 +/- 75.2 mg/dL) were determined. WMH was rated as absent (n = 56), punctate (n = 120), early confluent (n = 14), and confluent (n = 11). RESULTS: The baseline brain parenchymal fraction of the entire cohort was 0.80 +/- 0.02 with a mean annual brain volume change of -0.40 +/- 0.29%. Univariate analysis demonstrated a higher rate of brain atrophy in older subjects (p = 0.0001), in those with higher HbA1c (p = 0.0001), higher body mass index (p = 0.02), high alcohol intake (p = 0.04), severe WMH (p = 0.03), and in APOE epsilon4 carriers (p = 0.07). Multivariate analysis suggested that baseline brain parenchymal fraction, HbA1c, and WMH score explain a major proportion of variance in the rates of brain atrophy in the cohort (corrected R2 = 0.27; p = 0.0001). CONCLUSIONS: Neurologically asymptomatic elderly experience continuing brain volume loss, which appears to accelerate with age. Glycated hemoglobin A (HbA1c) was identified as a risk factor for a greater rate of brain atrophy. Clustering of factors associated with the so-called metabolic syndrome in subjects with high HbA1c suggests a link between this syndrome and late-life brain tissue loss.

Dedoussis GV, Skoumas J, Pitsavos C, Choumerianou DM, Genschel J, Schmidt H, Stefanadis C. · Laboratory of Molecular Biology, Department of Science of Dietetics-Nutrition, Harokopio University of Athens, Athens, Greece. · Eur J Clin Invest. · Pubmed #15200491 No free full text.

Abstract: BACKGROUND: Familial hypercholesterolaemia (FH) is caused by mutations in the low-density lipoprotein receptor gene and the gene encoding apolipoprotein B-100, affecting one in 500 individuals. METHODS: One hundred and eighty-three Greek FH patients were screened for mutations on the LDLR and ApoB genes. RESULTS: We identified mutations in 67 probands and 11 relatives. Sixteen mutations located in eight different exons and the promoter of the LDLR were discovered. Among them 10 were missense mutations (C6W, S265R, A370T, Q363P, D365E, V408M, A410T, A517T, G528D, G571E), two were nonsense mutations (Q363X and C660X), three were splice defects (2140 + 5G-->A and 2140 + 9C-->T, 1706 - 10G-->A), and one was a nucleotide substitution (- 45delT) on the promoter. None of the subjects carried any apoB mutation. The detection rate of mutations in this study was 43%. From the above mutations, A410T, A519T and the splice site defects 2140 + 9C-->T were detected for the first time in the Greek population. Among them V408M, G528D, C6W and S265R account for 73% of heterozygous FH probands. V408M mutation is more common in Central West, while C6W is more common in Central East. Separating the patients into two groups (receptor defective and receptor negative) we found that the receptor negative group had higher levels of total cholesterol, low-density lipoprotein cholesterol and higher prevalence of tendon xanthomas compared with the receptor-defective group. DISCUSSION: The homogenous molecular basis of familial hypercholesterolaemia in Greece facilitates the application of a DNA diagnostic strategy based on the origin of the patient. The early mutation analysis would add valuable information on the severity of the disease.

Dedoussis GV, Genschel J, Bochow B, Pitsavos C, Skoumas J, Prassa M, Lkhagvasuren S, Toutouzas P, Vogt A, Kassner U, Thomas HP, Schmidt H. · Department of Science Dietetics-Nutrition, Harokopio University of Athens, Greece. · Hum Mutat. · Pubmed #14974088 No free full text.

Abstract: We used the denaturing gradient gel electrophoresis (DGGE) method to define mutations in the promoter region, the 18 exons, and their flanking intronic sequences of the low-density lipoprotein (LDL) receptor gene LDLR, causing familial hypercholesterolemia (FH) phenotype in 100 German and in 100 Greek hypercholesterolemic individuals. In addition, we tested all patients for the presence of mutations in codons 3456-3553 of the gene encoding apolipoprotein B-100 (APOB). Twenty-six aberrant DGGE patterns were identified and subsequently directly sequenced. In LDLR, two novel missense mutations (c.1957G>T/p.V653F, c.647 G>A/p.C216Y) and one novel homozygous base substitution c.1-156 C>T in the repeat 2 of the promoter region were identified among German FH patients; one novel splice site c.1060+10C>G was identified among Greek FH patients. One of the German FH patients was a carrier for the mutations c.1171G>A/p.A391T and p.V653F, and two of the Greek FH patients were compound heterozygotes for the mutations c.1150C>T/p.Q384X and c.1158C>G/p.D386E. Two German FH patients carried the mutation p.R3500Q within APOB. Comparing the mutations within the LDLR gene of the two European FH populations, the German population seems to be more heterogeneous than the Greek cohort. Further studies in progress are trying to elucidate the responsiveness to drug therapy in association with LDLR genotype and the nutritional habits of the two FH populations.

deCampo A, Schallmoser K, Schmidt H, Toplak H, Kostner GM. · Department of Medicine, Diabetes and Metabolism, Karl-Franzens-University of Graz, 8036 Graz, Austria. · Atherosclerosis. · Pubmed #11472756 No free full text.

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Gutierrez G, Schneider A, Jobs J, Schmidt H, Korte A, Manns MP, Stuhrmann M. · Department of Gastroenterology and Hepatology, Medical School Hannover, Hannover, Germany. · Hum Mutat. · Pubmed #11013454 No free full text.

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Schmidt H, Kostner GM. · Institute of Medical Biochemistry, University of Graz, Harrachgasse 21, 8010, Graz, Austria. · Atherosclerosis. · Pubmed #10657581 No free full text.

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Streicher J, Valent P, Schmidt H, Sengölge G, Wagner O, Strobl W, Hörl WH, Derfler K. · Department of Nephrology, University of Vienna, Austria. · J Investig Med. · Pubmed #10510590 No free full text.

Abstract: BACKGROUND: Familial hypercholesterolemia (FH) is characterized by an autosomal dominantly inherited deficiency of LDL-receptor expression on the cell surface, leading to excess plasma LDL-cholesterol and severe premature atherosclerosis. In patients with heterozygous FH, a major therapeutic objective of conventional drug therapy is to stimulate maximally the residual cellular capacity to produce LDL-receptors via inhibition of endogenous cholesterol synthesis. In contrast, LDL-immunoapheresis aims at reducing the plasma LDL-cholesterol level by extracorporeal elimination of LDL particles. The present study investigates whether LDL-immunoapheresis applied in addition to conventional drug therapy is able to further stimulate residual LDL-receptor expression capacity in patients with heterozygous FH via the withdrawal of external cholesterol supply, thereby exerting a second accessory lipid lowering effect. METHODS: LDL-receptor expression--calculated by transforming mean fluorescence intensities into numbers of antibody binding sites per cell (S/C)--was determined flow-cytometrically on peripheral blood monocytes before and after LDL-apheresis. For a comparison with the maximum obtainable receptor expression capacity, in vitro stimulation experiments under completely LDL deficient conditions were performed. RESULTS: Prior to LDL-apheresis, LDL-receptor density was comparable in patients (N = 7; 2014 +/- 359 S/C) and controls (N = 10; 1782 +/- 252 S/C). Under in vitro conditions LDL-receptor expression of controls exceeded that of patients with FH by 1.6 times. Immediately after apheresis, LDL-receptor expression significantly increased to almost the same level as obtained by in vitro stimulation (3640 +/- 423 S/C and 3632 +/- 572 S/C). The LDL-receptor expression in FH subsequent to LDL-apheresis exhibited two patterns of kinetics [Type 1: maximal receptor stimulation (288 +/- 70%; P < 0.07) already during apheresis; Type 2: highest receptor density 24 hours after treatment (149 +/- 11%; P < 0.01)]. CONCLUSIONS: These results demonstrate that despite drug therapy, LDL-apheresis significantly stimulates the residual LDL-receptor expression in FH via the reduction of available extracellular cholesterol resulting in delayed reappearance of hypercholesterolemia in between treatments.

Widhalm K, Iro C, Lindemayr A, Schmidt H, Kostner G. · Dept. of Pediatrics, University of Vienna, Austria. · Hum Mutat. · Pubmed #10502834 No free full text.

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Behrens G, Dejam A, Schmidt H, Balks HJ, Brabant G, Körner T, Stoll M, Schmidt RE. · Department of Medicine, Hannover Medical School, Germany. · AIDS. · Pubmed #10416516 No free full text.

Abstract: OBJECTIVES: To evaluate metabolic abnormalities, beta-cell function, lipid profile and vascular risk factors in HIV patients on protease inhibitors (PI). DESIGN: Prospective cross-sectional study. METHODS: Thirty-eight HIV-1-infected patients receiving at least one PI were compared with 17 PI-naive HIV patients in an oral glucose tolerance test (OGTT). Serum glucose, insulin, proinsulin, and C-peptide were determined. The fasting lipid pattern was analysed using electrophoresis and the assessment of apolipoproteins including lipoprotein (a). Fibrinogen, homocysteine, and anticardiolipin antibodies were also assessed. RESULTS: Twenty-seven (71%) of the PI-treated group had detectable hyperlipidaemia. Isolated hypertriglyceridaemia was present in 12 patients (44%), two (7%) of them had type V and 10 (37%) subjects had type IV hyperlipidaemia (Frederickson classification). Type IIb hyperlipidaemia defined as an increase of both very-low-density lipoproteins (VLDL) and low-density lipoproteins (LDL) was found in 10 (36%) subjects, and five (18%) patients presented with isolated hypercholesterolaemia (type IIa). PI treatment was associated with significant higher fasting cholesterol, triglycerides, LDL and VLDL levels. Apolipoprotein B and E concentrations were significantly increased in patients receiving PI. Elevated concentrations of lipoprotein (a) (> 30 mg/dl) were detected in six (16%) of the hyperlipidaemic patients on PI. Eighteen (46%) patients on PI had impaired oral glucose tolerance and five (13%) had diabetes. Although four (24%) of the PI-naive patients were glucose intolerant, none had diabetes. Fasting concentrations and secretion response of insulin, proinsulin, and C-peptide to glucose ingestion was significantly increased in the PI-treated group suggesting a beta-cell dysfunction in addition to peripheral insulin resistance. Beta-cell abnormalities were associated with the abnormal lipid pattern and PI treatment. CONCLUSION: Combination drug regimens including PI are accompanied by impaired glucose tolerance, hyperproinsulinaemia as an indicator for beta-cell dysfunction, and lipid abnormalities proved to be significant risk factors for coronary heart disease. Moreover, PI may have an impact on the processing of proinsulin to insulin.

de Campo A, Toplak H, Wascher TC, Schallmoser K, Friehs A, Schmidt H, Kostner GM. · Ambulanz für Diabetes und Stoffwechsel, Medizinischen Universitätsklinik Graz. · Acta Med Austriaca. · Pubmed #10230472 No free full text.

Abstract: Heterozygous familial hypercholesterolemia (FH, prevalence 1:500) is a major cause of early atherosclerotic disease. Little is known about possible co-factors influencing individual patient's risk. We investigated this question in a large family carrying a new LDL-receptor-mutation. Genetic analysis of all exons of the LDL-receptor gene in the index case using polymerase chain reaction (PCR) and Denaturing Gradient Gel Electrophoresis (DGGE) revealed a previously unknown mutation in exon 10 (GAC > ACC, D471N, "FH Graz-1"). Investigation of 21 family members (15 females, 6 males), aged 17 to 86 years, revealed 9 female and 4 male carriers of the mutation. 7 female carriers aged 17 to 58 years show no clinical signs of macrovascular disease. An 86-year old female patient, who was asymptomatic until 85, recently suffered a transient cerebral ischemic attack. All these females were normotensive. The only hypertensive 76-year old patient (ex-smoker with a history of 15 pack years) suffers from angina pectoris. 2 male carriers of the mutation (32 and 38 years old) are asymptomatic. A 65-year old patient suffers from cardiovascular disease. A 49-year old patient had a coronary artery bypass graft after a myocardial infarction at the age of 37. Additionally he has a history of bilateral thrombendarterectomy of the carotid arteries and suffers from bilateral peripheral artery disease. This patient also carries the apoE-genotype 4/3, which might be responsible for his poor response to stain therapy, and needs extracorporal lipid elimination (LDL-C > 200 mg/dl under drug therapy). Both of his daughters are homozygous for the apoE-allele 3 and and responded well to stain therapy. Genetic analysis in patients with FH assures diagnosis, but is not sufficient to determine the individual patient's risk. A precise clinical examination remains the gold standard for individual risk evaluation.

Varret M, Rabès JP, Saint-Jore B, Cenarro A, Marinoni JC, Civeira F, Devillers M, Krempf M, Coulon M, Thiart R, Kotze MJ, Schmidt H, Buzzi JC, Kostner GM, Bertolini S, Pocovi M, Rosa A, Farnier M, Martinez M, Junien C, Boileau C. · Hôpital Necker-Enfants Malades, Institut National de la Santé et de la Recherche Médicale, Unit 383, Université René Descartes, 75743 Paris Cedex 15, France. · Am J Hum Genet. · Pubmed #10205269 links to  free full text

Abstract: Autosomal dominant hypercholesterolemia (ADH), one of the most frequent hereditary disorders, is characterized by an isolated elevation of LDL particles that leads to premature mortality from cardiovascular complications. It is generally assumed that mutations in the LDLR and APOB genes account for ADH. We identified one large French pedigree (HC2) and 12 additional white families with ADH in which we excluded linkage to the LDLR and APOB, implicating a new locus we named "FH3." A LOD score of 3.13 at a recombination fraction of 0 was obtained at markers D1S2892 and D1S2722. We localized the FH3 locus to a 9-cM interval at 1p34.1-p32. We tested four regional markers in another set of 12 ADH families. Positive LOD scores were obtained in three pedigrees, whereas linkage was excluded in the others. Heterogeneity tests indicated linkage to FH3 in approximately 27% of these non-LDLR/non-APOB ADH families and implied a fourth locus. Radiation hybrid mapping located four candidate genes at 1p34.1-p32, outside the critical region, showing no identity with FH3. Our results show that ADH is genetically more heterogeneous than conventionally accepted.

Ebhardt M, Schmidt H, Doerk T, Tietge U, Haas R, Manns MP, Schmidtke J, Stuhrmann M. · Institut fuer Humangenetik, Medizinische Hochschule Hannover, Germany. · Hum Mutat. · Pubmed #10090484 No free full text.

Abstract: In order to obtain a survey of the mutations being prevalent in Northern Germany and to enable molecular genetic testing for families with clinically diagnosed familial hypercholesterolemia (FH), we screened 46 unrelated German individuals with elevated LDL levels for mutations in the 18 exons and their flanking intron sequences including the promotor region of the LDL receptor (LDLR) gene. In addition, we tested all patients for the presence of mutations in the gene coding for apolipoprotein B-100 (apoB-100). We detected 15 mutations affecting the LDLR gene, 8 of which, designated A29S, 195insAT, 313+1insG, 553insG, 680insGGACAAATCTG, D200N, E267K and L411V have not yet been reported. One patient is heterozygous for the double mutant N543H and 2393del9Bp. Two patients carried the mutation R3500Q (Arg-->Glu) within the apoB-100 gene.