Project description:In this study 3 pooling experiments were performed. In each of the 3 cohorts, a 'case' and a 'control' blood pool was compared - the goal being to identify single nucleotide polymorphisms with significantly different estimated pooling allele frequencies between cases and controls. For cohort 1, 100 individuals with blue eye color were placed in one pool (the 'control' pool) and 100 individuals with brown eye color were placed in another pool ( the 'case' pool). In cohort 2, 131 individuals with age-related macular degeneration were placed in one pool, with 216 control individuals in another pool. In cohort 3, 100 individuals with pseudoexfoliation syndrome were placed in a case pool - in this case the cohort 2 control sample was used as 'controls'. The blue/brown pools were hybridized to Illumina HumanHap550 arrays. The cohort 2 and 3 pools were hybridized to Illumina 1M arrays. After processing, the raw data are summarized to give pooling allele frequency estimates for each pool. The abstract from the paper describing these data is as follows: Genome-wide association studies (GWAS) have now successfully identified important genetic variants associated with many human traits and diseases. The high cost of genotyping arrays in large datasets remains the major barrier to wider utilization of GWAS. We have developed a novel method in which whole blood from cases and controls respectively is pooled prior to DNA extraction for genotyping. We demonstrate proof of principle by clearly identifying the associated variants for eye color, age-related macular degeneration and pseudoexfoliation syndrome in cohorts not previously studied. Blood pooling has the potential to reduce GWAS cost by several orders of magnitude and dramatically shorten gene discovery time. This method has profound implications for translation of modern genetic approaches to a multitude of diseases and traits yet to be analysed by GWAS, and will enable developing nations to participate in GWAS. Pools were typed with Illumina arrays. Estimates of pooling allele frequency were obtained.

Project description:In this study 3 pooling experiments were performed. In each of the 3 cohorts, a 'case' and a 'control' blood pool was compared - the goal being to identify single nucleotide polymorphisms with significantly different estimated pooling allele frequencies between cases and controls. For cohort 1, 100 individuals with blue eye color were placed in one pool (the 'control' pool) and 100 individuals with brown eye color were placed in another pool ( the 'case' pool). In cohort 2, 131 individuals with age-related macular degeneration were placed in one pool, with 216 control individuals in another pool. In cohort 3, 100 individuals with pseudoexfoliation syndrome were placed in a case pool - in this case the cohort 2 control sample was used as 'controls'. The blue/brown pools were hybridized to Illumina HumanHap550 arrays. The cohort 2 and 3 pools were hybridized to Illumina 1M arrays. After processing, the raw data are summarized to give pooling allele frequency estimates for each pool. The abstract from the paper describing these data is as follows: Genome-wide association studies (GWAS) have now successfully identified important genetic variants associated with many human traits and diseases. The high cost of genotyping arrays in large datasets remains the major barrier to wider utilization of GWAS. We have developed a novel method in which whole blood from cases and controls respectively is pooled prior to DNA extraction for genotyping. We demonstrate proof of principle by clearly identifying the associated variants for eye color, age-related macular degeneration and pseudoexfoliation syndrome in cohorts not previously studied. Blood pooling has the potential to reduce GWAS cost by several orders of magnitude and dramatically shorten gene discovery time. This method has profound implications for translation of modern genetic approaches to a multitude of diseases and traits yet to be analysed by GWAS, and will enable developing nations to participate in GWAS.

Project description:Dogs are commonly used models of human inherited retinal disorders. Because the dog retina contains a macula-like region, dogs are susceptible to maculopathies with many shared genetic etiologies with humans. Human macular gene expression has been characterized and provides insight into the underlying basis of macular disease. We sought to compare macular gene expression profiles in dogs and humans and interrogate macular disease-associated genes for differential expression between macula and periphery. RNA sequencing was performed on 8mm samples of the dog macular region and superior peripheral region, sampling retina and retinal pigmented epithelium/choroid separately. Read sequences were mapped to CanFam3.1 and raw read counts were analyzed to determine significantly differentially expressed genes between macula and periphery within each tissue. A similar analytic pipeline was used with a published dataset of human samples to allow direct dog/human comparisons. Pathways and processes involved in significantly DEGs were identified using the Database for Annotation, Visualization and Integrated Discovery. Dogs and humans shared the extent and direction of macular retinal differential gene expression, with multiple shared biological pathways implicated in differential expression. There were fewer similarities between dog and human in the supporting tissues of the retina (the RPE, choroid, sclera). Many genes implicated in heritable retinal and macular disorders in both dogs and humans were differentially expressed between macula and periphery. Approximately 2/3 of genes associated with human age-related macular degeneration were differentially expressed in at least one human tissue, whereas approximately half were differentially expressed in at least one dog tissue. This work underpins the dog macular retinal region as analogous to the human macula in terms of differential gene expression. Whilst age-related maculopathy has not been described in dogs, evidence supports the study of aging of the macula and susceptibility to age-associated pathology in dogs.

Dataset Information

Illumina Omni5 SNP chip genotyping of MacTel cases and unaffected controls for a genome-wide association study

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