Michael Krawczak

Christian-Albrechts-Universität zu Kiel, Kiel, Schleswig-Holstein, Germany

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Publications (159)1011.08 Total impact

  • Article: Association Between Variants of PRDM1 and NDP52 and Crohns Disease, Based on Exome Sequencing and Functional Studies.
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    ABSTRACT: BACKGROUND& AIMS: Genome-wide association studies (GWASs) have identified 140 Crohn's disease (CD) susceptibility loci. For most loci, the variants that cause disease are not known and the genes affected by these variants have not been identified. We aimed to identify variants that cause CD through detailed sequencing, genetic association, expression, and functional studies. METHODS: We sequenced whole exomes of 42 unrelated subjects with Crohn's disease (CD) and 5 healthy individuals (controls), and then filtered single-nucleotide variants by incorporating association results from meta-analyses of CD GWASs and in silico mutation effect prediction algorithms. We then genotyped 9348 patients with CD, 2868 with ulcerative colitis, and 14,567 controls, and associated variants analyzed in functional studies using materials from patients and controls and in vitro model systems. RESULTS: We identified rare missense mutations in PR domain-containing1 (PRDM1) and associated these with CD. These increased proliferation of T cells and secretion of cytokines upon activation, and increased expression of the adhesion molecule L-selectin. A common CD risk allele, identified in GWASs, correlated with reduced expression of PRDM1 in ileal biopsies and peripheral blood mononuclear cells (combined P=1.6×0(-8)). We identified an association between CD and a common missense variant, Val248Ala, in nuclear domain 10 protein 52 (NDP52) (P=4.83×10(-9)). We found that this variant impairs the regulatory functions of NDP52 to inhibit NFκB activation of genes that regulate inflammation and affect stability of proteins in toll-like receptor pathways. CONCLUSIONS: We have extended GWAS results and provide evidence that variants in PRDM1 and NDP52 determine susceptibility to CD. PRDM1 maps adjacent to a CD interval identified in GWASs and encodes a transcription factor expressed by T and B cells. NDP52 is an adaptor protein that functions in selective autophagy of intracellular bacteria and signaling molecules, supporting the role for autophagy in pathogenesis of CD.
    Gastroenterology 04/2013; · 11.68 Impact Factor
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    Dataset: Lessig 2003 3
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    Dataset: Lessig 2003 1
  • Article: Estimating trace-suspect match probabilities for singleton Y-STR haplotypes using coalescent theory.
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    ABSTRACT: Estimation of match probabilities for singleton haplotypes of lineage markers, i.e. for haplotypes observed only once in a reference database augmented by a suspect profile, is an important problem in forensic genetics. We compared the performance of four estimators of singleton match probabilities for Y-STRs, namely the count estimate, both with and without Brenner's so-called 'kappa correction', the surveying estimate, and a previously proposed, but rarely used, coalescent-based approach implemented in the BATWING software. Extensive simulation with BATWING of the underlying population history, haplotype evolution and subsequent database sampling revealed that the coalescent-based approach is characterized by lower bias and lower mean squared error than the uncorrected count estimator and the surveying estimator. Moreover, in contrast to the two count estimators, both the surveying and the coalescent-based approach exhibited a good correlation between the estimated and true match probabilities. However, although its overall performance is thus better than that of any other recognized method, the coalescent-based estimator is still computation-intense on the verge of general impracticability. Its application in forensic practice therefore will have to be limited to small reference databases, or to isolated cases of particular interest, until more powerful algorithms for coalescent simulation have become available.
    Forensic science international. Genetics 12/2012; · 2.42 Impact Factor
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    Article: Genetic characterization of northeastern Italian population isolates in the context of broader European genetic diversity.
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    ABSTRACT: Population genetic studies on European populations have highlighted Italy as one of genetically most diverse regions. This is possibly due to the country's complex demographic history and large variability in terrain throughout the territory. This is the reason why Italy is enriched for population isolates, Sardinia being the best-known example. As the population isolates have a great potential in disease-causing genetic variants identification, we aimed to genetically characterize a region from northeastern Italy, which is known for isolated communities. Total of 1310 samples, collected from six geographically isolated villages, were genotyped at >145 000 single-nucleotide polymorphism positions. Newly genotyped data were analyzed jointly with the available genome-wide data sets of individuals of European descent, including several population isolates. Despite the linguistic differences and geographical isolation the village populations still show the greatest genetic similarity to other Italian samples. The genetic isolation and small effective population size of the village populations is manifested by higher levels of genomic homozygosity and elevated linkage disequilibrium. These estimates become even more striking when the detected substructure is taken into account. The observed level of genetic isolation in Friuli-Venezia Giulia region is more extreme according to several measures of isolation compared with Sardinians, French Basques and northern Finns, thus proving the status of an isolate.European Journal of Human Genetics advance online publication, 19 December 2012; doi:10.1038/ejhg.2012.229.
    European journal of human genetics: EJHG 12/2012; · 3.56 Impact Factor
  • Article: Association studies of the copy-number variable Ss-defensin cluster on 8p23.1 in adenocarcinoma and chronic pancreatitis.
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    ABSTRACT: BACKGROUND: Human Ss-defensins are a family of antimicrobial peptides located at the mucosal surface. Both sequence multi-site variations (MSV) and copy-number variants (CNV) of the defensin-encoding genes are associated with increased risk for various diseases, including cancer and inflammatory conditions such as psoriasis and acute pancreatitis. In a case--control study, we investigated the association between MSV in DEFB104 as well as defensin gene (DEF) cluster copy number (CN), and pancreatic ductal adenocarcinoma (PDAC) and chronic pancreatitis (CP). RESULTS: Two groups of PDAC (N=70) and CP (N=60) patients were compared to matched healthy control groups CARLA1 (N=232) and CARLA2 (N=160), respectively. Four DEFB104 MSV were haplotyped by PCR, cloning and sequencing. DEF cluster CN was determined by multiplex ligation-dependent probe amplification.Neither the PDAC nor the CP cohorts show significant differences in the DEFB104 haplotype distribution compared to the respective control groups CARLA1 and CARLA2, respectively.The diploid DEF cluster CN exhibit a significantly different distribution between PDAC and CARLA1 (Fisher's exact test P=0.027), but not between CP and CARLA2 (P=0.867). CONCLUSION: Different DEF cluster b CN distribution between PDAC patients and healthy controls indicate a potential protective effect of higher CNs against the disease.
    BMC Research Notes 11/2012; 5(1):629.
  • Article: Genome-wide investigation of gene-environment interactions in colorectal cancer.
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    ABSTRACT: Colorectal cancer (CRC), one of the most frequent neoplasias worldwide, has both genetic and environmental causes. As yet, however, gene-environment (G × E) interactions in CRC have been studied mostly for a small number of candidate genes only. Therefore, we investigated the possible interaction, in CRC etiology, between single-nucleotide polymorphisms (SNPs) on the one hand, and overweight, smoking and alcohol consumption on the other, at a genome-wide level. To this end, we adopted a two-tiered approach comprising a case-only screening stage I (314 cases) and a case-control validation stage II (259 cases, 1,002 controls). Interactions with the smallest p value in stage I were verified in stage II using multiple logistic regression analysis adjusted for sex and age. In addition, we specifically studied known CRC-associated SNPs for possible G × E interactions. Upon adjustment for sex and age, and after allowing for multiple testing, however, only a single SNP (rs1944511) was found to be involved in a statistically significant interaction, namely with overweight (multiplicity-corrected p = 0.042 in stage II). Several other G × E interactions were nominally significant but failed correction for multiple testing, including a previously reported interaction between rs9929218 and alcohol consumption that also emerged in our candidate SNP study (nominal p = 0.008). Notably, none of the interactions identified in our genome-wide analysis was with a previously reported CRC-associated SNP. Our study therefore highlights the potential of an "agnostic" genome-wide approach to G × E analysis.
    Human Genetics 11/2012; · 5.07 Impact Factor
  • Article: Genetic and functional identification of the likely causative variant for cholesterol gallstone disease at the ABCG5/8 lithogenic locus.
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    ABSTRACT: BACKGROUND & AIMS: The sterolin locus (ABCG5/ABCG8) has been solidly shown to confer susceptibility for cholesterol gallstone disease in humans. Both the responsible variant and the molecular mechanism causing an increased incidence of gallstones in these patients have as yet not been identified. METHODS: Genetic mapping utilized patient samples from Germany (2808 cases, 2089 controls), Chile (680 cases, 442 controls), Denmark (366 cases, 766 controls), India (247 cases, 224 controls) and China (280 cases, 244 controls). Analysis of allelic imbalance in cDNA samples from human liver (N=22) was performed using pyrosequencing. Transiently transfected HEK293 cells were used for [3H]-cholesterol export assays, analysis of protein expression and localisation of allelic constructs. RESULTS: Through fine mapping in German and Chilean samples, a ∼250kB disease-associated interval could be defined for this locus. Lack of allelic imbalance or allelic splicing of the ABCG5 and ABCG8 transcripts in human liver limited the search to coding SNPs. Subsequent mutation detection and genotyping yielded two disease-associated variants ABCG5-R50C (p=4.94×10(-9) ) and ABCG8-D19H (p=1.74×10(-10) ) in high pair-wise LD (r(2) =0.95). [3H]-cholesterol export assays of allelic constructs harbouring these genetic candidate variants demonstrated increased transport activity (3.2-fold, p=0.003) only for the ABCG8-19H variant, which was also superior in nested logistic regression models in German (p=0.018), Chilean (p=0.030) and Chinese (p=0.040) patient samples. CONCLUSION: This variant thus provides a molecular basis for biliary cholesterol hypersecretion as the mechanism for cholesterol gallstone formation thereby drawing a link between "post-genomic" and "pre-genomic" pathophysiological knowledge about this common complex disorder. (HEPATOLOGY 2012.).
    Hepatology 08/2012; · 11.66 Impact Factor
  • Article: Genome-wide search for novel human uORFs and N-terminal protein extensions using ribosomal footprinting.
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    ABSTRACT: So far, the annotation of translation initiation sites (TISs) has been based mostly upon bioinformatics rather than experimental evidence. We adapted ribosomal footprinting to puromycin-treated cells to generate a transcriptome-wide map of TISs in a human monocytic cell line. A neural network was trained on the ribosomal footprints observed at previously annotated AUG translation initiation codons (TICs), and used for the ab initio prediction of TISs in 5062 transcripts with sufficient sequence coverage. Functional interpretation suggested 2994 novel upstream open reading frames (uORFs) in the 5' UTR, 1406 uORFs overlapping with the coding sequence, and 546 N-terminal protein extensions. The TIS detection method was validated on the basis of previously published alternative TISs and uORFs. Among primates, TICs in newly annotated TISs were significantly more conserved than control codons, both for AUGs and near-cognate codons. The transcriptome-wide map of novel candidate TISs derived as part of the study will shed further light on the way in which human proteome diversity is influenced by alternative translation initiation and regulation.
    Genome Research 08/2012; · 13.61 Impact Factor
  • Article: Recurrence of gallstones after cholecystectomy is associated with ABCG5/8 genotype.
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    ABSTRACT: BACKGROUND: Gallstone disease is a frequent and economically highly relevant disorder, with cholecystectomy representing one of the most frequently performed operations world-wide. Gallstone recurrence after cholecystectomy is associated with complications such as biliary sepsis and pancreatitis. As yet, variant ABCG8-D19H is the most widely recognized genetic risk factor for gallstone disease. The aim of the study is to investigate whether ABCG8-D19H is associated with gallstone recurrence after cholecystectomy. METHODS: Two thousand three hundred and eight patients from an earlier study of gallstone risk factors were re-contacted by mail, leading to 1,915 patients with available clinical and genetic information. Symptomatic gallstone recurrence was established if it occurred more than six months after surgery. Median follow-up time after cholecystectomy was eight years. RESULTS: Gallstones recurred in 37 patients (1.9 %). ABCG-D19H was found to be significantly associated with gallstone recurrence (p = 0.034). The allelic odds ratio was 1.97 (95 % CI 1.12-∞). In a multivariate logistic regression analysis adjusted for age, sex, BMI and type of surgery, ABCG8-D19H remained a significant predictor, both in the total cohort (p = 0.024) and in the subgroup for whom information on type and scheduling of surgery was available (N = 1,650, p = 0.020). CONCLUSIONS: ABCG8-D19H is a predictor of gallstone recurrence, a major long term postoperative biliary complication. Moreover, the observed association also reemphasizes the importance of the sterolin transporter for stone formation.
    Journal of Gastroenterology 08/2012; · 4.16 Impact Factor
  • Article: 'Sifting the significance from the data' - the impact of high-throughput genomic technologies on human genetics and health care.
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    ABSTRACT: This report is of a round-table discussion held in Cardiff in September 2009 for Cesagen, a research centre within the Genomics Network of the UK's Economic and Social Research Council (ESRC). The meeting was arranged to explore ideas as to the likely future course of human genomics.
    Human genomics 08/2012; 6(1):11.
  • Article: Decision-making in familial database searching: KI alone or not alone?
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    ABSTRACT: We consider the comparison of hypotheses "parent-child" or "full siblings" against the alternative of "unrelated" for pairs of individuals for whom DNA profiles are available. This is a situation that occurs repeatedly in familial database searching. A decision rule that uses both the kinship index (KI), also known as the likelihood ratio, and the identity-by-state statistic (IBS) was advocated in a recent report as superior to the use of KI alone. Such proposal appears to conflict with the Neyman-Pearson Lemma of statistics, which states that the likelihood ratio alone provides the most powerful criterion for distinguishing between any two simple hypotheses. We therefore performed a simulation study that was two orders of magnitude larger than in the previous report, and our results corroborate the theoretical expectation that KI alone provides a better decision rule than KI combined with IBS.
    Forensic science international. Genetics 06/2012; · 2.42 Impact Factor
  • Article: Copy number variation in patients with cervical artery dissection.
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    ABSTRACT: Cervical artery dissection (CeAD) occurs in healthy young individuals and often entails ischemic stroke. Skin biopsies from most CeAD-patients show minor connective tissue alterations. We search for rare genetic deletions and duplication that may predispose to CeAD. Forty-nine non-traumatic CeAD-patients with electron microscopic (EM) alterations of their dermal connective tissue (EM+ patients) and 21 patients with normal connective tissue in skin biopsies (EM- patients) were analyzed. Affymetrix 6.0 microarrays (Affymetrix) from all patients were screened for copy number variants (CNVs). CNVs absent from 403 control subjects and from 2402 published disease-free individuals were considered as CeAD-associated. The genetic content of undentified CNVs was analyzed by means of the Gene Ontology (GO) Term Mapper to detect associations with biological processes. In 49 EM+ patients we identified 13 CeAD-associated CNVs harboring 83 protein-coding genes. In 21 EM- patients we found five CeAD-associated CNVs containing only nine genes (comparison of CNV gene density between the groups: Mann-Whitney P=0.039). Patients' CNVs were enriched for genes involved in extracellular matrix organization (COL5A2, COL3A1, SNTA1, P=0.035), collagen fibril organization COL5A2, COL3A1, (P=0.0001) and possibly for genes involved in transforming growth factor beta (TGF)-beta receptor signaling pathway (COL3A1, DUPS22, P=0.068). We conclude that rare genetic variants may contribute to the pathogenesis of CeAD, in particular in patients with a microscopic connective tissue phenotype.European Journal of Human Genetics advance online publication, 23 May 2012; doi:10.1038/ejhg.2012.82.
    European journal of human genetics: EJHG 05/2012; · 3.56 Impact Factor
  • Article: Genetic investigation of FOXO3A requires special attention due to sequence homology with FOXO3B.
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    ABSTRACT: Our study demonstrates that the genetic investigation of forkhead box O3A gene (FOXO3A), a validated human longevity gene, is greatly hampered by the fact that its exonic regions have 99% sequence homology with the FOXO3B pseudogene. If unaccounted for, this high degree of homology can cause serious genotyping or sequencing errors. Here, we present an experimental set-up that allows reliable data generation for the highly homologous regions and that can be used for the evaluation of assay specificity. Using this design, we exemplarily showed FOXO3A-specific results for two single-nucleotide polymorphisms (SNPs) (rs4945816 and rs4946936) that are significantly associated with longevity in our centenarian-control sample (P(each)=0.0008). Because both SNPs are located in the 3' untranslated region of FOXO3A, they could be of functional relevance for the longevity phenotype. Our experimental set-up can be used for reliable and reproducible data generation for further sequencing and genotyping studies of FOXO3A with the aim of discovering new SNPs of functional relevance.European Journal of Human Genetics advance online publication, 16 May 2012; doi:10.1038/ejhg.2012.83.
    European journal of human genetics: EJHG 05/2012; · 3.56 Impact Factor
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    Article: Paternal kin bias in the agonistic interventions of adult female rhesus macaques (Macaca mulatta)
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    ABSTRACT: When agonistic interventions are nepotistic, individuals are expected to side more often with kin but less often against kin in comparison with non-kin. As yet, however, few mammal studies have been in a position to test the validity of this assertion with respect to paternal relatedness. We therefore used molecular genetic kinship testing to assess whether adult female rhesus macaques (Macaca mulatta) from the free-ranging colony of Cayo Santiago (Puerto Rico) bias their interventions in ongoing dyadic aggressive interactions towards maternal and paternal half-sisters compared with unrelated females. It turned out that females supported maternal half-sisters significantly more often than paternal half-sisters or non-kin regardless of the costs associated with such interventions. Similarly, females targeted maternal half-sisters significantly less often than non-kin when this was associated with high costs. Unrelated females provided significantly higher mean rates of both high- and low-cost support to each other than did paternal half-sisters. However, females targeted paternal half-sisters significantly less often than non-kin when targeting was at low cost, suggesting that females refrain from intervening against paternal half-sisters. Our data confirm the general view that coalition formation in female mammals is a function of both the level of maternal relatedness and of the costs of intervention. The patterns of coalition formation among paternal kin were found to be more complex, and may also differ across species, but clear evidence for paternal kin discrimination was observed in female rhesus as predicted by kin selection theory.
    Behavioral Ecology and Sociobiology 04/2012; 61(2):205-214. · 3.18 Impact Factor
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    Article: The changing landscape of genetic testing and its impact on clinical and laboratory services and research in Europe
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    ABSTRACT: The arrival of new genetic technologies that allow efficient examination of the whole human genome (microarray, next-generation sequencing) will impact upon both laboratories (cytogenetic and molecular genetics in the first instance) and clinical/medical genetic services. The interpretation of analytical results in terms of their clinical relevance and the predicted health status poses a challenge to both laboratory and clinical geneticists, due to the wealth and complexity of the information obtained. There is a need to discuss how to best restructure the genetic services logistically and to determine the clinical utility of genetic testing so that patients can receive appropriate advice and genetic testing. To weigh up the questions and challenges of the new genetic technologies, the European Society of Human Genetics (ESHG) held a series of workshops on 10 June 2010 in Gothenburg. This was part of an ESHG satellite symposium on the ‘Changing landscape of genetic testing’, co-organized by the ESHG Genetic Services Quality and Public and Professional Policy Committees. The audience consisted of a mix of geneticists, ethicists, social scientists and lawyers. In this paper, we summarize the discussions during the workshops and present some of the identified ways forward to improve and adapt the genetic services so that patients receive accurate and relevant information. This paper covers ethics, clinical utility, primary care, genetic services and the blurring boundaries between healthcare and research.
    European Journal of HumanGenetics 03/2012; 20(9):911-916. · 4.40 Impact Factor
  • Article: Collaborative genetic mapping of 12 forensic short tandem repeat (STR) loci on the human X chromosome.
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    ABSTRACT: A large number of short tandem repeat (STR) markers spanning the entire human X chromosome have been described and established for use in forensic genetic testing. Due to their particular mode of inheritance, X-STRs often allow easy and informative haplotyping in kinship analyses. Moreover, some X-STRs are known to be tightly linked so that, in combination, they constitute even more complex genetic markers than each STR taken individually. As a consequence, X-STRs have proven particularly powerful in solving complex cases of disputed blood relatedness. However, valid quantification of the evidence provided by X-STR genotypes in the form of likelihood ratios requires that the recombination rates between markers are exactly known. In a collaborative family study, we used X-STR genotype data from 401 two- and three-generation families to derive valid estimates of the recombination rates between 12 forensic markers widely used in forensic testing, namely DXS10148, DXS10135, DXS8378 (together constituting linkage group I), DXS7132, DXS10079, DXS10074 (linkage group II), DXS10103, HPRTB, DXS10101 (linkage group III), DXS10146, DXS10134 and DXS7423 (linkage group IV). Our study is the first to simultaneously allow for mutation and recombination in the underlying likelihood calculations, thereby obviating the bias-prone practice of excluding ambiguous transmission events from further consideration. The statistical analysis confirms that linkage groups I and II are transmitted independently from one another whereas linkage groups II, III and IV are characterised by inter-group recombination fractions that are notably smaller than 50%. Evidence was also found for recombination within all four linkage groups, with recombination fraction estimates ranging as high as 2% in the case of DXS10146 and DXS10134.
    Forensic science international. Genetics 03/2012; 6(6):778-84. · 2.42 Impact Factor
  • Article: SFRS10--a splicing factor gene reduced in human obesity?
    Cell metabolism 03/2012; 15(3):265-6; author reply 267-9. · 17.35 Impact Factor
  • Article: How to distinguish genetically between an alleged father and his monozygotic twin: a thought experiment.
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    ABSTRACT: Recently, a first direct estimate of the single base-pair substitution rate in the human germline was derived from genome-wide DNA sequence data. This result has shed new light upon the question of whether cutting-edge molecular genetic analysis could, in a paternity dispute, potentiate discrimination between two alleged fathers who are monozygotic (MZ) twins. Such paternity cases are not infrequent and usually receive a high level of public attention. We performed a 'thought experiment', the outcome of which strongly suggests that, by a combination of currently available laboratory techniques, paternity testing is indeed feasible in the context of MZ twins. Taking into consideration what is known about the biology of the human male germline, we would predict that >80% of the offspring of one twin brother would carry at least one germline mutation that would be detectable in the sperm of their father, but not in that of the other twin.
    Forensic science international. Genetics 12/2011; 6(5):e129-30. · 2.42 Impact Factor
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    Article: Empirical evaluation reveals best fit of a logistic mutation model for human Y-chromosomal microsatellites.
    Arne Jochens, Amke Caliebe, Uwe Rösler, Michael Krawczak
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    ABSTRACT: The rate of microsatellite mutation is dependent upon both the allele length and the repeat motif, but the exact nature of this relationship is still unknown. We analyzed data on the inheritance of human Y-chromosomal microsatellites in father-son duos, taken from 24 published reports and comprising 15,285 directly observable meioses. At the six microsatellites analyzed (DYS19, DYS389I, DYS390, DYS391, DYS392, and DYS393), a total of 162 mutations were observed. For each locus, we employed a maximum-likelihood approach to evaluate one of several single-step mutation models on the basis of the data. For five of the six loci considered, a novel logistic mutation model was found to provide the best fit according to Akaike's information criterion. This implies that the mutation probability at the loci increases (nonlinearly) with allele length at a rate that differs between upward and downward mutations. For DYS392, the best fit was provided by a linear model in which upward and downward mutation probabilities increase equally with allele length. This is the first study to empirically compare different microsatellite mutation models in a locus-specific fashion.
    Genetics 12/2011; 189(4):1403-11. · 4.01 Impact Factor

Institutions

  • 2002–2013
    • Christian-Albrechts-Universität zu Kiel
      • • Institut für Experimentelle Medizin
      • • UKSH Institut für Medizinische Informatik und Statistik
      • • Institute of Clinical Molecular Biology
      Kiel, Schleswig-Holstein, Germany
  • 2012
    • Aalborg University
      • Department of Mathematical Sciences
      Aalborg, Region North Jutland, Denmark
    • John Radcliffe Hospital
      Oxford, ENG, United Kingdom
    • Duke University
      Durham, NC, USA
  • 2011
    • Universität Bern
      Bern, BE, Switzerland
  • 1993–2011
    • Medizinische Hochschule Hannover
      • Institute for Human Genetics
      Hannover, Lower Saxony, Germany
  • 2010
    • Beijing Genomics Institute
      Shenzhen, Guangdong Sheng, China
  • 2004–2010
    • Universitätsklinikum Schleswig - Holstein
      Kiel, Schleswig-Holstein, Germany
  • 2008–2009
    • Erasmus Universiteit Rotterdam
      • • Department of Internal Medicine
      • • Department of Forensic Molecular Biology
      Rotterdam, South Holland, Netherlands
    • Leibniz Institute for Age Research - Fritz Lipmann Institute
      • Genome Analysis
      Jena, Thuringia, Germany
    • Universität Freiburg
      Freiburg, Lower Saxony, Germany
  • 2002–2008
    • Cardiff University
      • • School of Medicine
      • • Institute of Medical Genetics
      • • School of Computer Science and Informatics
      Cardiff, WLS, United Kingdom
  • 1990–2008
    • Charles University in Prague
      Praha, Hlavni mesto Praha, Czech Republic
  • 2007
    • Erasmus MC
      • Department of Forensic Molecular Biology
      Rotterdam, South Holland, Netherlands
    • Leuphana University Lüneburg
      Lüneburg, Lower Saxony, Germany
  • 2006
    • Universität Heidelberg
      • Institute of Human Genetics
      Heidelberg, Baden-Wuerttemberg, Germany
  • 2004–2005
    • Humboldt-Universität zu Berlin
      • Institute of General Medicine
      Berlin, Land Berlin, Germany
  • 2002–2004
    • University of Wales
      Cardiff, WLS, United Kingdom
  • 2003
    • University of Leipzig
      • Institut für Rechtsmedizin
      Leipzig, Saxony, Germany
  • 2002–2003
    • San Diego Zoo
      San Diego, CA, USA
  • 2000
    • University of Puerto Rico, Medical Sciences Campus
      San Juan, San Juan, Puerto Rico