Bayesian modeling of recombination events in bacterial populations

Background: We consider the discovery of recombinant segments jointly with their origins within multilocus DNA sequences from bacteria representing heterogeneous populations of fairly closely related species. The currently available methods for recombination detection capable of probabilistic characterization of uncertainty have a limited applicability in practice as the number of strains in a data set increases. Results: We introduce a Bayesian spatial structural model representing the continuum of origins over sites within the observed sequences, including a probabilistic characterization of uncertainty related to the origin of any particular site. To enable a statistically accurate and practically feasible approach to the analysis of large-scale data sets representing a single genus, we have developed a novel software tool (BRAT, Bayesian Recombination Tracker) implementing the model and the corresponding learning algorithm, which is capable of identifying the posterior optimal structure and to estimate the marginal posterior probabilities of putative origins over the sites. Conclusion: A multitude of challenging simulation scenarios and an analysis of real data from seven housekeeping genes of 120 strains of genus Burkholderia are used to illustrate the possibilities offered by our approach. The software is freely available for download at URL http://web.abo.fi/fak/ mnf//mate/jc/software/brat.html

MYO9B polymorphisms in multiple sclerosis

"Single-nucleotide polymorphisms (SNPs) in the 30 region of myosin IXB (MYO9B) gene have recently been reported to associate with different inflammatory or autoimmune diseases. We monitored for the association of MYO9B variants to multiple sclerosis (MS) in four Northern European populations. First, 18 SNPs including 6 SNPs with previous evidence for association to immune disorders, were tested in 730 Finnish MS families, but no linkage or family-based association was observed. To ensure the power to detect variants with a modest effect size, we further analyzed 10 variants in 899 Finnish cases and 1325 controls, and in a total of 1521 cases and 1476 controls from Denmark, Norway and Sweden, but found no association. Our results thereby do not support a major function of the tested MYO9B variants in MS. European Journal of Human Genetics (2009) 17, 840-843; doi: 10.1038/ejhg.2008.251; published online 14 January 2009""Single-nucleotide polymorphisms (SNPs) in the 30 region of myosin IXB (MYO9B) gene have recently been reported to associate with different inflammatory or autoimmune diseases. We monitored for the association of MYO9B variants to multiple sclerosis (MS) in four Northern European populations. First, 18 SNPs including 6 SNPs with previous evidence for association to immune disorders, were tested in 730 Finnish MS families, but no linkage or family-based association was observed. To ensure the power to detect variants with a modest effect size, we further analyzed 10 variants in 899 Finnish cases and 1325 controls, and in a total of 1521 cases and 1476 controls from Denmark, Norway and Sweden, but found no association. Our results thereby do not support a major function of the tested MYO9B variants in MS. European Journal of Human Genetics (2009) 17, 840-843; doi: 10.1038/ejhg.2008.251; published online 14 January 2009""Single-nucleotide polymorphisms (SNPs) in the 30 region of myosin IXB (MYO9B) gene have recently been reported to associate with different inflammatory or autoimmune diseases. We monitored for the association of MYO9B variants to multiple sclerosis (MS) in four Northern European populations. First, 18 SNPs including 6 SNPs with previous evidence for association to immune disorders, were tested in 730 Finnish MS families, but no linkage or family-based association was observed. To ensure the power to detect variants with a modest effect size, we further analyzed 10 variants in 899 Finnish cases and 1325 controls, and in a total of 1521 cases and 1476 controls from Denmark, Norway and Sweden, but found no association. Our results thereby do not support a major function of the tested MYO9B variants in MS. European Journal of Human Genetics (2009) 17, 840-843; doi: 10.1038/ejhg.2008.251; published online 14 January 2009"Peer reviewe

Pre-Bilaterian Origins of the Hox Cluster and the Hox Code: Evidence from the Sea Anemone, Nematostella vectensis

BACKGROUND: Hox genes were critical to many morphological innovations of bilaterian animals. However, early Hox evolution remains obscure. Phylogenetic, developmental, and genomic analyses on the cnidarian sea anemone Nematostella vectensis challenge recent claims that the Hox code is a bilaterian invention and that no “true” Hox genes exist in the phylum Cnidaria. METHODOLOGY/PRINCIPAL FINDINGS: Phylogenetic analyses of 18 Hox-related genes from Nematostella identify putative Hox1, Hox2, and Hox9+ genes. Statistical comparisons among competing hypotheses bolster these findings, including an explicit consideration of the gene losses implied by alternate topologies. In situ hybridization studies of 20 Hox-related genes reveal that multiple Hox genes are expressed in distinct regions along the primary body axis, supporting the existence of a pre-bilaterian Hox code. Additionally, several Hox genes are expressed in nested domains along the secondary body axis, suggesting a role in “dorsoventral” patterning. CONCLUSIONS/SIGNIFICANCE: A cluster of anterior and posterior Hox genes, as well as ParaHox cluster of genes evolved prior to the cnidarian-bilaterian split. There is evidence to suggest that these clusters were formed from a series of tandem gene duplication events and played a role in patterning both the primary and secondary body axes in a bilaterally symmetrical common ancestor. Cnidarians and bilaterians shared a common ancestor some 570 to 700 million years ago, and as such, are derived from a common body plan. Our work reveals several conserved genetic components that are found in both of these diverse lineages. This finding is consistent with the hypothesis that a set of developmental rules established in the common ancestor of cnidarians and bilaterians is still at work today

The CALM1 core promoter polymorphism is not associated with hip osteoarthritis in a United Kingdom Caucasian population.

OBJECTIVE: A convincing genetic association with hip osteoarthritis (OA) of a functional single nucleotide polymorphism (SNP) in the core promoter of the calmodulin 1 gene CALM1 was recently reported in a Japanese population. The T-allele of the SNP encoded OA susceptibility and this was mediated by a reduced expression of CALM1. Our objective was to assess whether the SNP was also associated with hip OA in UK Caucasians. METHODS: The SNP was genotyped in 920 cases that had undergone elective joint replacement of the hip due to end-stage primary OA and in 752 age-matched controls. RESULTS: Our study had greater than 97% power to observe an effect comparable to that seen in the Japanese study. However, there was no significant difference (P< or =0.05) in genotype or allele frequencies between our cases and our controls. There was also no significant difference when the cases were stratified by sex. CONCLUSION: Our data on a cohort of 1672 individuals implies that the CALM1 core promoter polymorphism is not a risk factor for OA etiology in Caucasians. Our study does not call in to question the veracity of the Japanese report. Instead it highlights the heterogeneous nature of OA genetic susceptibility

Genetic association analysis of LRCH1 as an osteoarthritis susceptibility locus.

OBJECTIVE: A genetic association with knee osteoarthritis (OA) of a single nucleotide polymorphism (SNP) in intron 1 of the LRCH1 gene was recently reported in a UK Caucasian case-control sample and confirmed in a Newfoundland Caucasian sample. Our objective was to assess whether the SNP was associated with OA in our large UK Caucasian sample. METHODS: The SNP was genotyped in 1521 cases that had undergone elective joint replacement of the hip (1098 cases), of the knee (340 cases) or of the hip and knee (83 cases) due to end-stage primary OA. The SNP was also genotyped in 736 controls of similar ages in the cases. RESULTS: There was no significant difference (all P-values >0.05) in genotype or allele frequencies between our cases and our controls. There was also no significant difference when the cases were stratified by sex, by joint replaced or by sex combined with joint replaced. CONCLUSION: Our data on 2257 individuals implies that the LRCH1 intron 1 SNP is not a risk factor for OA aetiology of the knee or of the hip in our UK Caucasian sample