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Association Result (association + result)
Selected AbstractsReplication of genetic associations as pseudoreplication due to shared genealogyGENETIC EPIDEMIOLOGY, Issue 6 2009Noah A. Rosenberg Abstract The genotypes of individuals in replicate genetic association studies have some level of correlation due to shared descent in the complete pedigree of all living humans. As a result of this genealogical sharing, replicate studies that search for genotype-phenotype associations using linkage disequilibrium between marker loci and disease-susceptibility loci can be considered as "pseudoreplicates" rather than true replicates. We examine the size of the pseudoreplication effect in association studies simulated from evolutionary models of the history of a population, evaluating the excess probability that both of a pair of studies detect a disease association compared to the probability expected under the assumption that the two studies are independent. Each of nine combinations of a demographic model and a penetrance model leads to a detectable pseudoreplication effect, suggesting that the degree of support that can be attributed to a replicated genetic association result is less than that which can be attributed to a replicated result in a context of true independence. Genet. Epidemiol. 33:479,487, 2009. © 2009 Wiley-Liss, Inc. [source] No Association between SNP rs498055 on Chromosome 10 and Late-Onset Alzheimer Disease in Multiple DatasetsANNALS OF HUMAN GENETICS, Issue 1 2008Xueying Liang Summary SNP rs498055 in the predicted gene LOC439999 on chromosome 10 was recently identified as being strongly associated with late-onset Alzheimer disease (LOAD). This SNP falls within a chromosomal region that has engendered continued interest generated from both preliminary genetic linkage and candidate gene studies. To independently evaluate this interesting candidate SNP we examined four independent datasets, three family-based and one case-control. All the cases were late-onset AD Caucasian patients with minimum age at onset , 60 years. None of the three family samples or the combined family-based dataset showed association in either allelic or genotypic family-based association tests at p < 0.05. Both original and OSA two-point LOD scores were calculated. However, there was no evidence indicating linkage no matter what covariates were applied (the highest LOD score was 0.82). The case-control dataset did not demonstrate any association between this SNP and AD (all p-values > 0.52). Our results do not confirm the previous association, but are consistent with a more recent negative association result that used family-based association tests to examine the effect of this SNP in two family datasets. Thus we conclude that rs498055 is not associated with an increased risk of LOAD. [source] Characterization of a QTL region affecting clinical mastitis and protein yield on BTA6ANIMAL GENETICS, Issue 5 2009H. Nilsen Summary Quantitative trait loci affecting clinical mastitis were detected and fine mapped to a narrow region on bovine chromosome 6 in the Norwegian Red cattle population. The region includes the casein gene cluster and several candidate genes thought to influence clinical mastitis. The most significant results were found for SNPs within the Mucin 7 gene. This gene encodes an antimicrobial peptide and constitutes part of the first line of defence for the mucosal immune system. Detection of long haplotypes extending several Mb may indicate that artificial selection has influenced the haplotype structures in the region. A search for selection sweeps supports this observation and coincides with association results found both by single SNP and haplotype analyses. Our analyses identified haplotypes carrying quantitative trait loci alleles associated with high protein yield and simultaneously fewer incidences of clinical mastitis. The fact that such haplotypes are found in relative high frequencies in Norwegian Red may reflect the combined breeding goal that is characterized by selection for both milk production and disease resistance. The identification of these haplotypes raises the possibility of overcoming the unfavourable genetic correlation between these traits through haplotype-assisted selection. [source] Depression and chronic medical illnesses in Asian older adults: the role of subjective health and functional statusINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 11 2007Matthew Niti Abstract Objective Depression in elderly is reportedly associated with a number of specific chronic illnesses. Whether each of these co-morbid associations results uniquely from disease-specific psychobiological responses or is mediated by non-specific factors like subjective health and functional status is unclear. Method Analysis of data of 2,611 community-dwelling Chinese aged 55 and older, including depressive symptoms defined by Geriatric Depression Scale score,,,5 and self-reports of specific chronic illnesses. Results The prevalence of depressive symptoms was 13.3%, lower in those without chronic illness (7.5%), and higher in those with illnesses (13.2,24.2%). Crude Odds Ratios (OR) were significantly elevated for hypertension, eye disorders, diabetes, arthritis, ischemic heart disease, asthma/COPD, stroke, osteoporosis, heart failure, thyroid problem, and gastric problem. In multivariable analyses, only asthma/COPD [OR:2.85, 95% Confidence Intervals (CI): 1.36, 5.98], gastric problem (OR:2.64, 95% CI: 1.11, 6.29), arthritis (OR:1.87, 95% CI: 1.02, 3.42) and heart failure (OR:2.11, 95% CI: 0.98, 4.58) remained independently associated with depressive symptoms, after adjusting for comorbidities, subjective health and functional status, cognitive functioning, smoking, alcohol, psychosocial and demographic variables. Conclusion Most comorbid associations of depressive symptoms with specific chronic illnesses are explained by accompanying poor self-reported health and functional status, but some illnesses probably have a direct psychobiological basis. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||