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Effect of population structure corrections on the results of association mapping tests in complex maize diversity panels.

ABSTRACT: Association mapping of sequence polymorphisms underlying the phenotypic variability of quantitative agronomical traits is now a widely used method in plant genetics. However, due to the common presence of a complex genetic structure within the plant diversity panels, spurious associations are expected to be highly frequent. Several methods have thus been suggested to control for panel structure. They mainly rely on ad hoc criteria for selecting the number of ancestral groups; which is often not evident for the complex panels that are commonly used in maize. It was thus necessary to evaluate the effect of the selected structure models on the association mapping results. A real maize data set (342 maize inbred lines and 12,000 SNPs) was used for this study. The panel structure was estimated using both Bayesian and dimensional reduction methods, considering an increasing number of ancestral groups. Effect on association tests depends in particular on the number of ancestral groups and on the trait analyzed. The results also show that using a high number of ancestral groups leads to an over-corrected model in which all causal loci vanish. Finally the results of all models tested were combined in a meta-analysis approach. In this way, robust associations were highlighted for each analyzed trait.

SUBMITTER: Mezmouk S

PROVIDER: S-EPMC3057001 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

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Effect of population structure corrections on the results of association mapping tests in complex maize diversity panels.

Mezmouk Sofiane S Dubreuil Pierre P Bosio Mickaël M Décousset Laurent L Charcosset Alain A Praud Sébastien S Mangin Brigitte B

TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik 20110111 6

Association mapping of sequence polymorphisms underlying the phenotypic variability of quantitative agronomical traits is now a widely used method in plant genetics. However, due to the common presence of a complex genetic structure within the plant diversity panels, spurious associations are expected to be highly frequent. Several methods have thus been suggested to control for panel structure. They mainly rely on ad hoc criteria for selecting the number of ancestral groups; which is often not ...[more]

PMID: 21221527

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Project description:Vaccines to prevent capsular group B meningococcal disease have been based on proteins, as the polysaccharide capsule was deemed unsuitable due to its similarity to human tissues. Outer membrane vesicle (OMV) vaccines have been targeted at specific capsular group B epidemics in Cuba, Norway, and New Zealand, with the major immunogen determined as porin A (PorA). Subcapsular protein vaccines aim to increase breadth of coverage of meningococcal strains, by the inclusion of protein variants from many different clonal complexes (ccs). Using scalable and portable genomic techniques, it is possible to study the diversity of OMV and subcapsular proteins in relevant meningococcal populations. Shotgun proteomics identified 461 proteins in the OMVs derived from NZ98/254, a component of the Bexsero® vaccine, with a complex proteome comprised of outer membrane proteins and proteins from other cellular compartments. Amino acid sequences for 24 selected proteins were catalogued within the PubMLST Neisseria database as part of the OMV peptide Typing (OMVT) scheme. Of the 24 proteins included, there was variation in the extent of diversity and association with ccs from the most conserved peptides FbpA (NEISp0578) and putative periplasmic proteins (NEISp1063) to the most diverse TbpA (NEISp1690). There were 1752 OMVTs identified amongst 2492/3506 isolates. OMVTs were further grouped into clusters (identical at ≥18 peptide sequences), 45.3% of isolates were assigned to one of 27 OMVT clusters. Both OMVTs and clusters were strongly associated with cc, genogroup and recombinant Bexsero® antigens. The OMVT scheme represents an open-access, web-based tool for the systematic analysis of the multiple components of OMV vaccines, demonstrating that combinations of OMV proteins exist in discrete, non-overlapping combinations associated with both genogroup and Bexsero® Antigen Sequence type (BAST). This highly structured population of disease-causing meningococci is consistent with proposed effects of host immune selection and competition between allelic variants on meningococcal population structure. This has implications for future vaccine assessment, and development, especially the choice of antigen combinations. The methodology is portable and will facilitate region-specific WGS interrogation, allowing informed choices about vaccine development or implementation.

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Dataset Information

Effect of population structure corrections on the results of association mapping tests in complex maize diversity panels.

Publications

Effect of population structure corrections on the results of association mapping tests in complex maize diversity panels.

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