Genome-Wide Association Studies in an Isolated Founder Population from the Pacific Island of Kosrae

It has been argued that the limited genetic diversity and reduced allelic heterogeneity observed in isolated founder populations facilitates discovery of loci contributing to both Mendelian and complex disease. A strong founder effect, severe isolation, and substantial inbreeding have dramatically reduced genetic diversity in natives from the island of Kosrae, Federated States of Micronesia, who exhibit a high prevalence of obesity and other metabolic disorders. We hypothesized that genetic drift and possibly natural selection on Kosrae might have increased the frequency of previously rare genetic variants with relatively large effects, making these alleles readily detectable in genome-wide association analysis. However, mapping in large, inbred cohorts introduces analytic challenges, as extensive relatedness between subjects violates the assumptions of independence upon which traditional association test statistics are based. We performed genome-wide association analysis for 15 quantitative traits in 2,906 members of the Kosrae population, using novel approaches to manage the extreme relatedness in the sample. As positive controls, we observe association to known loci for plasma cholesterol, triglycerides, and C-reactive protein and to a compelling candidate loci for thyroid stimulating hormone and fasting plasma glucose. We show that our study is well powered to detect common alleles explaining ≥5% phenotypic variance. However, no such large effects were observed with genome-wide significance, arguing that even in such a severely inbred population, common alleles typically have modest effects. Finally, we show that a majority of common variants discovered in Caucasians have indistinguishable effect sizes on Kosrae, despite the major differences in population genetics and environment

Validating inflammatory bowel disease (IBD) in the Swedish National Patient Register and the Swedish Quality Register for IBD (SWIBREG)

Background: Both the Swedish National Patient Register (NPR) and the Swedish Quality Register for inflammatory bowel disease (IBD, SWIBREG) are important sources of research data and information. However, the validity of a diagnosis of IBD in these registers is unknown. Methods: Medical charts of 129 randomly selected patients from the NPR and 165 patients registered both in SWIBREG and the NPR were reviewed. Patients were classified according to standardized criteria for ulcerative colitis (UC), Crohns disease (CD), or IBD unclassified (IBD-U). Positive predictive values (PPVs) for UC, CD, IBD-U (only SWIBREG), or having any form of IBD were then calculated. Results: For cases with amp;gt;= 2 diagnoses of IBD in the NPR (hospitalizations or non-primary care outpatient visits), the PPV was 93% (95% CI: 87-97) for any IBD, 79% (66-88) for UC and 72% (60-82) for CD. In UC patients with amp;gt;= 2 UC diagnoses but never a CD diagnosis, the PPV increased to 90% (77-97). The PPV for CD in patients with amp;gt;= 2 CD diagnoses but never a UC diagnosis was 81% (67-91)). Combining data from SWIBREG (amp;gt;= 1 record) and the NPR (amp;gt;= 1 record), the PPV was 99% for any IBD (97-100), 96% (89-99) for UC, and 90% (82-96) for CD. Conclusion: The validity of the UC, CD, and IBD diagnoses is high in the NPR but even higher when cases were identified both in SWIBREG and the NPR. These results underline the need for a well-functioning Swedish Quality Register for IBD as a complement to the NPR.Funding Agencies|Swedish Quality Register for IBD (SWIBREG)</p

The Odin satellite. I. Radiometer design and test

International audienc

The Odin satellite. I. Radiometer design and test

International audienc