14 research outputs found
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Competitive Market Analysis of Transplant Centers and Discrepancy of Wait-Listing of Recipients for Kidney Transplantation
Background: There are over 250 kidney transplant programs in the USA. Objective: To determine if highly competitive regions, defined as regions with a higher number of transplant centers, will approve and wait-list more end-stage renal disease (ESRD) candidates for transplant despite consistent incidence and prevalence of ESRD nationwide. Methods: ESRD Network and OPTN data completed in 2011 were obtained from all transplant centers including listing data, market saturation, market share, organs transplanted, and ESRD prevalence. Herfindahl-Hirschman Index (HHI) was used to measure the size of firms in relation to the industry to determine the amount of competition. Results: States were separated into 3 groups (HHI1800 considered highly concentrated). The percentage of ESRD patients listed in competitive, moderate, and highly concentrated regions were 19.73%, 17.02%, and 13.75%, respectively. The ESRD listing difference between competitive versus highly concentrated was significant (p<0.05). Conclusion: When there is strong competition without a dominant center as defined by the HHI, the entire state tends to list more patients for transplant to drive up their own center’s market share. Our analysis of the available national data suggests a discrepancy in access for ESRD patient to transplantation due to transplant center competition
Mutations in different pigmentation genes are associated with parallel melanism in island flycatchers
The independent evolution of similar traits across multiple taxa provides some of the most compelling evidence of natural selection. Little is known, however, about the genetic basis of these convergent or parallel traits: are they mediated by identical or different mutations in the same genes, or unique mutations in different genes? Using a combination of candidate gene and reduced representation genomic sequencing approaches, we explore the genetic basis of and the evolutionary processes that mediate similar plumage colour shared by isolated populations of the Monarcha castaneiventris flycatcher of the Solomon Islands. A genome-wide association study (GWAS) that explicitly controlled for population structure revealed that mutations in known pigmentation genes are the best predictors of parallel plumage colour. That is, entirely black or melanic birds from one small island share an amino acid substitution in the melanocortin-1 receptor (MC1R), whereas similarly melanic birds from another small island over 100 km away share an amino acid substitution in a predicted binding site of agouti signalling protein (ASIP). A third larger island, which separates the two melanic populations, is inhabited by birds with chestnut bellies that lack the melanic MC1R and ASIP allelic variants. Formal FST outlier tests corroborated the results of the GWAS and suggested that strong, directional selection drives the near fixation of the MC1R and ASIP variants across islands. Our results, therefore, suggest that selection acting on different mutations with large phenotypic effects can drive the evolution of parallel melanism, despite the relatively small population size on islands
Data from: Mutations in different pigmentation genes are associated with parallel melanism in island flycatchers
The independent evolution of similar traits across multiple taxa provides some of the most compelling evidence of natural selection. Little is known, however, about the genetic basis of these convergent or parallel traits: are they mediated by identical or different mutations in the same genes, or unique mutations in different genes? Using a combination of candidate gene and reduced representation genomic sequencing approaches, we explore the genetic basis of and the evolutionary processes that mediate similar plumage colour shared by isolated populations of the Monarcha castaneiventris flycatcher of the Solomon Islands. A genome-wide association study (GWAS) that explicitly controlled for population structure revealed that mutations in known pigmentation genes are the best predictors of parallel plumage colour. That is, entirely black or melanic birds from one small island share an amino acid substitution in the melanocortin-1 receptor (MC1R), whereas similarly melanic birds from another small island over 100 km away share an amino acid substitution in a predicted binding site of agouti signalling protein (ASIP). A third larger island, which separates the two melanic populations, is inhabited by birds with chestnut bellies that lack the melanic MC1R and ASIP allelic variants. Formal FST outlier tests corroborated the results of the GWAS and suggested that strong, directional selection drives the near fixation of the MC1R and ASIP variants across islands. Our results, therefore, suggest that selection acting on different mutations with large phenotypic effects can drive the evolution of parallel melanism, despite the relatively small population size on islands
MClade_MC1R_ASIP.hmp
A hapmap (text) file containing all of the SNPs and their genotypes in each individual that were used in the genome-wide association analysis. (See TASSEL documentation for more info. on the hapmap format)
Mon_filter10X.hmp
A hapmap file containing SNPs for the same data set, but in this case reads were filtered with a depth minimum of 10X (versus 5X) before SNP calling