Research Topics
Genomes and GenesSpecies | Osman El-MaarriSummaryAffiliation: University of Bonn Country: Germany Publications
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Publications
Methods: DNA methylationOsman El-Maarri
Institute of experimental heamatology and transfusion medecine, Sigmund Freud strs 25, 53127 Bonn
Adv Exp Med Biol 544:197-204. 2003- SIRPH analysis: SNuPE with IP-RP-HPLC for quantitative measurements of DNA methylation at specific CpG sitesOsman El-Maarri
Institute of Experimental Haematology and Transfusion Medicine, Bonn, Germany
Methods Mol Biol 287:195-205. 2004..The ratio of the ddCTP to the ddTTP gives the fraction of the methylated cytosines at that specific CpG site... 
A systematic search for DNA methyltransferase polymorphisms reveals a rare DNMT3L variant associated with subtelomeric hypomethylationOsman El-Maarri
Institute of Experimental Hematology and Transfusion Medicine, University of Bonn, Bonn, Germany
Hum Mol Genet 18:1755-68. 2009....- Gender specific differences in levels of DNA methylation at selected loci from human total blood: a tendency toward higher methylation levels in malesOsman El-Maarri
Institute of Experimental Hematology and Transfusion Medicine, University of Bonn, Sigmund Freud Str 25, 53127, Bonn, Germany
Hum Genet 122:505-14. 2007..This observed difference could be due to the process of X chromosome inactivation or merely to the presence of an additional X chromosome in female cells or could be a result of downstream effects of sex determination... 
Methylation at global LINE-1 repeats in human blood are affected by gender but not by age or natural hormone cyclesOsman El-Maarri
Institute of Experimental Hematology and Transfusion Medicine, University of Bonn, Bonn, Germany
PLoS ONE 6:e16252. 2011..In conclusion, neither natural cycle of hormones nor age has a detectable effect on the LINE-1 methylation in peripheral blood cells, while gender remains an important factor...- Familial hydatidiform molar pregnancy: the germline imprinting defect hypothesis?O El-Maarri
Institute of Experimental Hematology and Transfusion Medicine, Bonn, Germany
Curr Top Microbiol Immunol 301:229-41. 2006..In this chapter, we summarize what is known about methylation aberrations in HMs and examine more closely the proposed hypothesis of a maternal germline imprinting defect... - Lack of F8 mRNA: a novel mechanism leading to hemophilia AOsman El-Maarri
Institute of Experimental Hematology and Transfusion Medicine, Sigmund Freud Str 25, 53127 Bonn, Germany
Blood 107:2759-65. 2006..These findings strongly suggest that the cause of HA in this patient is either absence or rapid degradation of the F8 mRNA, which points to a novel mechanism leading to HA... - DNA methylation and human diseasesOsman El-Maarri
Institute of Experimental Haematology and Transfusion Medicine, Sigmund-Freud Str 25, 53127 Bonn, Germany
Adv Exp Med Biol 544:135-44. 2003 - A rapid, quantitative, non-radioactive bisulfite-SNuPE- IP RP HPLC assay for methylation analysis at specific CpG sitesOsman El-Maarri
Institute of Experimental Haematology and Transfusion Medicine, Sigmund Freud Strasse 25, 53105 Bonn, Germany
Nucleic Acids Res 30:e25. 2002..The assay is linear, highly reproducible and several sites can be measured simultaneously in one reaction. It can be semi-automated and eliminates the need for cloning and sequencing of individual bisulfite PCR products... - Patients with familial biparental hydatidiform moles have normal methylation at imprinted genesOsman El-Maarri
Institute of Experimental Haematology and Transfusion Medicine, Bonn, Germany
Eur J Hum Genet 13:486-90. 2005.... - Association of COMT genotypes with S-COMT promoter methylation in growth-discordant monozygotic twins and healthy adultsFelix Schreiner
Pediatric Endocrinology Division, Children s Hospital, University of Bonn, Adenauerallee 119, Bonn 53113, Germany
BMC Med Genet 12:115. 2011..So far, studies investigating the epigenetic variability of the S-COMT (soluble COMT) promoter region mainly focused on phenotypical aspects, and results have been controversial... - Maternal alleles acquiring paternal methylation patterns in biparental complete hydatidiform molesOsman El-Maarri
Institute of Experimental Haematology and Transfusion Medicine, Bonn 53105, Germany
Hum Mol Genet 12:1405-13. 2003..The defective 19q13.4 locus may have led to the development of variable degrees of 'faulty' paternal marks on the maternal chromosomes... - Methylation of L1Hs promoters is lower on the inactive X, has a tendency of being higher on autosomes in smaller genomes and shows inter-individual variability at some lociHeike Singer
Institute of Experimental Hematology and Transfusion Medicine, University of Bonn, Bonn, Germany
Hum Mol Genet 21:219-35. 2012..In summary, loci-specific LINE-1 methylation levels show considerable plasticity and depend on genomic position and constitution... - Measurements of DNA methylation at seven loci in various tissues of CD1 miceLaurynas Daugela
Institute of Experimental Hematology and Transfusion Medicine, University of Bonn, Bonn, Germany
PLoS ONE 7:e44585. 2012..Additional studies that examine large numbers of loci may be required to further understand the factors that influence stability of DNA methylation... - SIRPH: an HPLC-based SNuPE for quantitative methylation measurement at specific CpG sitesHeike Singer
Institute of Experimental Haematology and Transfusion Medicine, University of Bonn, Bonn, Germany
Methods Mol Biol 791:89-100. 2011..This method is highly accurate, reproducible, quantitative, and suitable for analysis of as little as 50 ng of PCR product derived from limited starting materials... - Optimization of quantitative MGMT promoter methylation analysis using pyrosequencing and combined bisulfite restriction analysisThomas Mikeska
Department of Neuropathology, University of Bonn Medical Center, Sigmund Freud Str 25, D 53105 Bonn, Germany
J Mol Diagn 9:368-81. 2007..The optimized pyrosequencing assay performed best and provides a sensitive, robust, and easy-to-use method for quantitative assessment of MGMT methylation, for both snap-frozen and paraffin-embedded specimens... - Monitoring the progression of the in vitro selection of nucleic acid aptamers by denaturing high-performance liquid chromatographyJens Muller
Institute of Experimental Haematology and Transfusion Medicine, University of Bonn, Sigmund Freud Str 25, 53127, Bonn, Germany
Anal Bioanal Chem 390:1033-7. 2008..We employ denaturing HPLC and describe for the first time an experimental set-up that is useful both for analysis of the progression of in-vitro selection experiments and for separation of distinct aptamer sequences... - New insight into the molecular basis of hemophilia AJohannes Oldenburg
Institute of Experimental Haematology and Transfusion Medicine, Bonn, Germany
Int J Hematol 83:96-102. 2006..Moreover, the proof of an absence of F8 messenger RNA (mRNA) in one patient points to either a defect in the expression of F8 mRNA or its rapid degradation, which may represent a novel mechanism leading to HA... - Impact of the menstrual cycle on circulating cell-free DNAMartin Pölcher
Department of Gynecology and Obstetrics, Center for Integrated Oncology, Bonn University Medical Center, Sigmund Freud Str 25, D 53105 Bonn, Germany
Anticancer Res 30:2235-40. 2010..To determine serum levels of circulating cell-free DNA (cfDNA) throughout the stages of endometrial proliferation and apoptosis during the menstrual cycle... - Sensitive determination of BRAF copy number in clinical samples by pyrosequencingPrashanth Setty
Department of Neuropathology, University of Bonn, Germany
Diagn Mol Pathol 20:148-57. 2011..In summary, we have established a pyrosequencing-based assay allowing precise detection of BRAF copy numbers in DNA extracted from clinical samples... - Haemophilia A in a female caused by coincidence of a Swyer syndrome and a missense mutation in factor VIII geneRalph M Loreth
Thromb Haemost 95:747-8. 2006 - Epimutations in Prader-Willi and Angelman syndromes: a molecular study of 136 patients with an imprinting defectKarin Buiting
Institut fur Humangenetik, Universitatsklinikum Essen, Essen, Germany
Am J Hum Genet 72:571-7. 2003..These data suggest that this imprinting defect results from a failure to erase the maternal imprint during spermatogenesis... - Epigenetic reprogramming in mouse primordial germ cellsPetra Hajkova
, FR 8.2 Genetik, Postfach 151150, , Germany
Mech Dev 117:15-23. 2002..Aberrant epigenetic reprogramming in the germ line would cause the inheritance of epimutations that may have consequences for human diseases as suggested by studies on mouse models... - DNA-methylation analysis by the bisulfite-assisted genomic sequencing methodPetra Hajkova
Max-Planck-Institute for Molecular Genetics, Berlin, Germany
Methods Mol Biol 200:143-54. 2002 - Detection of heterozygous large deletions in the antithrombin gene using multiplex polymerase chain reaction and denatured high performance liquid chromatographyAnna Pavlova
Institute of Transfusion Medicine and Immunohaematolgy, , 60526 Frankfurt/M, Germany
Haematologica 91:1264-7. 2006..Using this approach we identified heterozygous deletions in four patients: the deletions affected exons 1 and 2, exon 7 and the whole antithrombin gene... - Familial molar tissues due to mutations in the inflammatory gene, NALP7, have normal postzygotic DNA methylationUgljesa Djuric
Departments of Human Genetics and Obstetrics and Gynecology, McGill University Health Center, Montreal, Canada, H3G 1A4
Hum Genet 120:390-5. 2006..The known role of NALP7 in apoptosis and inflammation pinpoints previously unrecognized pathways that could directly or indirectly underlie the abnormal methylation of imprinted genes in molar tissues... - DNA methylation at promoter regions regulates the timing of gene activation in Xenopus laevis embryosIrina Stancheva
Department of Biomedical Sciences, Genes and Development Group, The University of Edinburgh, Hugh Robson Building, Edinburgh EH8 9XD, United Kingdom
Dev Biol 243:155-65. 2002..Our results suggest that DNA methylation has a role in regulating the timing of gene activation at MBT in Xenopus laevis embryos...