Search results for "IMPUTATION"
showing 10 items of 57 documents
Genome- wide association study with additional genetic and post-transcriptional analyses reveals novel regulators of plasma factor XI levels
2017
International audience; Coagulation factor XI (FXI) has become increasingly interesting for its role in pathogenesis of thrombosis. While elevated plasma levels of FXI have been associated with venous thromboembolism and ischemic stroke, its deficiency is associated with mild bleeding. We aimed to determine novel genetic and post-transcriptional plasma FXI regulators.We performed a genome-wide association study (GWAS) for plasma FXI levels, using novel data imputed to the 1000 Genomes reference panel. Individual GWAS analyses, including a total of 16,169 European individuals from the ARIC, GHS, MARTHA and PROCARDIS studies, were meta-analysed and further replicated in 2,045 individuals from…
Genome-wide Analyses Identify KIF5A as a Novel ALS Gene
2018
© 2018 Elsevier Inc.
Lost to follow-up in the Norwegian mother, father and child cohort study.
2021
Background The aim of pregnancy cohorts was to understand causes and development of health and disease throughout the life course. A major challenge in cohort studies is to avoid selection bias from loss to follow-up. Objective The aim of this study was to describe what characterises drop out from the Norwegian Mother, Father and Child Cohort Study (MoBa), and provide a resource to inform the interpretation of results from analysis of cohort data. Methods We estimated loss to follow-up in subsets of participants that responded to questionnaire waves in MoBa through an eight-year period and described characteristics of participants who responded to follow-ups. Within each wave of questionnai…
Polygenic Risk Scores and Physical Activity
2020
Supplemental digital content is available in the text.
Treating missing data in a clinical neuropsychological dataset--data imputation.
2001
Missing data frequently reduce the applicability of clinically collected data in research requiring multivariate statistics. In data imputation, missing values are replaced by predicted values obtained from models based on auxiliary information. Our aim was to complete a clinical child neuropsychological data set containing 5.2% of missing observations. This was to be used in research requiring multivariate statistics. We compared four data imputation methods by artificially deleting some data. A real-donor imputation method which preserved the parameter estimates and which predicted the observed values with acceptable accuracy was used to complete the data set. In addressing the lack of st…
Meta-analysis of genome-wide association studies of attention-deficit/hyperactivity disorder
2010
Contains fulltext : 87688.pdf (Publisher’s version ) (Closed access) OBJECTIVE: Although twin and family studies have shown attention-deficit/hyperactivity disorder (ADHD) to be highly heritable, genetic variants influencing the trait at a genome-wide significant level have yet to be identified. As prior genome-wide association studies (GWAS) have not yielded significant results, we conducted a meta-analysis of existing studies to boost statistical power. METHOD: We used data from four projects: a) the Children's Hospital of Philadelphia (CHOP); b) phase I of the International Multicenter ADHD Genetics project (IMAGE); c) phase II of IMAGE (IMAGE II); and d) the Pfizer-funded study from the…
L'imputazione dei dati mancanti: l'effetto sui parametri di un Extended Logistic Rasch Model
2008
Il problema dei dati mancanti è abbastanza comune nella ricerca empirica, specialmente nelle scienze sociali in cui il tentativo di misurazione di quantità non direttamente osservabili (variabili latenti)avviene attraverso la somministrazione di test o questionari costituiti da più item. I modelli statistici finalizzati alla soluzione di tale problema richiedono, in genere, un elevato numero di osservazioni per ogni unità coinvolta nell’analisi. In un contesto multivariato il problema si amplifica, poiché nel modello sono considerati più item per ciascuna osservazione: la probabilità, quindi, di avere almeno un dato mancante non è irrilevante ed è, inoltre, crescente al crescere del numero …
Imputation Strategies for Missing Data in Environmental Time Series for An Unlucky Situation
2005
After a detailed review of the main specific solutions for treatment of missing data in environmental time series, this paper deals with the unlucky situation in which, in an hourly series, missing data immediately follow an absolutely anomalous period, for which we do not have any similar period to use for imputation. A tentative multivariate and multiple imputation is put forward and evaluated; it is based on the possibility, typical of environmental time series, to resort to correlations or physical laws that characterize relationships between air pollutants.
Comparison of HapMap and 1000 genomes reference panels in a large-scale genome-wide association study
2017
An increasing number of genome-wide association (GWA) studies are now using the higher resolution 1000 Genomes Project reference panel (1000G) for imputation, with the expectation that 1000G imputation will lead to the discovery of additional associated loci when compared to HapMap imputation. In order to assess the improvement of 1000G over HapMap imputation in identifying associated loci, we compared the results of GWA studies of circulating fibrinogen based on the two reference panels. Using both HapMap and 1000G imputation we performed a meta-analysis of 22 studies comprising the same 91,953 individuals. We identified six additional signals using 1000G imputation, while 29 loci were ass…
Genome-wide association and large-scale follow up identifies 16 new loci influencing lung function
2011
Pulmonary function measures reflect respiratory health and are used in the diagnosis of chronic obstructive pulmonary disease. We tested genome-wide association with forced expiratory volume in 1 second and the ratio of forced expiratory volume in 1 second to forced vital capacity in 48,201 individuals of European ancestry with follow up of the top associations in up to an additional 46,411 individuals. We identified new regions showing association (combined P < 5 x 10(-8)) with pulmonary function in or near MFAP2, TGFB2, HDAC4, RARB, MECOM (also known as EVI1), SPATA9, ARMC2, NCR3, ZKSCAN3, CDC123, C10orf11, LRP1, CCDC38, MMP15, CFDP1 and KCNE2. Identification of these 16 new loci may p…