SearcharxivSearch

arXiv subjects

Duchwan Ryu

Publications and source records attributed to Duchwan Ryu.

4 recordsLinked to original sources

mmcmcBayes:An R Package Implementing a Multistage MCMC Framework for Detecting the Differentially Methylated Regions

Identifying differentially methylated regions is an important task in epigenome-wide association studies, where differential signals often arise across groups of neighboring CpG sites. Many existing methods detect differentially methylated regions by aggregating CpG-level test results, which may limit their ability to capture complex regional methylation patterns. In this paper, we introduce the R package mmcmcBayes, which implements a multistage Markov chain Monte Carlo procedure for region-level detection of differentially methylated regions. The method models sample-wise regional methylation summaries using the alpha-skew generalized normal distribution and evaluates evidence for differential methylation between groups through Bayes factors. We use a multistage region-splitting strategy to refine candidate regions based on statistical evidence. We describe the underlying methodology and software implementation, and illustrate its performance through simulation studies and applications to Illumina 450K methylation data. The mmcmcBayes package provides a practical region-level alternative to existing CpG-based differentially methylated regions detection methods and includes supporting functions for summarizing, comparing, and visualizing detected regions.

stat.AP

Bayesian Functional Data Analysis over Dependent Regions and Its Application for Identification of Differentially Methylated Regions

We consider a Bayesian functional data analysis for observations measured as extremely long sequences. Splitting the sequence into a number of small windows with manageable length, the windows may not be independent especially when they are neighboring to each other. We propose to utilize Bayesian smoothing splines to estimate individual functional patterns within each window and to establish transition models for parameters involved in each window to address the dependent structure between windows. The functional difference of groups of individuals at each window can be evaluated by Bayes Factor based on Markov Chain Monte Carlo samples in the analysis. In this paper, we examine the proposed method through simulation studies and apply it to identify differentially methylated genetic regions in TCGA lung adenocarcinoma data.

stat.ME

Variable Selection with Random Survival Forest and Bayesian Additive Regression Tree for Survival Data

In this paper we utilize a survival analysis methodology incorporating Bayesian additive regression trees to account for nonlinear and additive covariate effects. We compare the performance of Bayesian additive regression trees, Cox proportional hazards and random survival forests models for censored survival data, using simulation studies and survival analysis for breast cancer with U.S. SEER database for the year 2005. In simulation studies, we compare the three models across varying sample sizes and censoring rates on the basis of bias and prediction accuracy. In survival analysis for breast cancer, we retrospectively analyze a subset of 1500 patients having invasive ductal carcinoma that is a common form of breast cancer mostly affecting older woman. Predictive potential of the three models are then compared using some widely used performance assessment measures in survival literature.

stat.AP

Generalized Integrated Functional Test for Regional Methylation Rates

Motivation: Methods are needed to test pre-defined genomic regions such as promoters for differential methylation in genome-wide association studies, where the number of samples is limited and the data have large amounts of measurement error. Results: We developed a new statistical test, the generalized integrated functional test (GIFT), which tests for regional differences in methylation based on differences in the functional relationship between methylation percent and location of the CpG sites within a region. In this method, subject-specific functional profiles are first estimated, and the average profile within groups is compared between groups using an ANOVA-like test. Simulations and analyses of data obtained from patients with chronic lymphocytic leukemia indicate that GIFT has good statistical properties and is able to identify promising genomic regions. Further, GIFT is likely to work with multiple different types of experiments since different smoothing functions can be used to estimate the functional relationship between methylation percent and CpG site location. Availability and Implementation: Matlab code for GIFT and sample data are available at http://biostat.gru.edu/~dryu/research.html. Contact: rpodolsk@med.wayne.edu or dryu@gru.edu

q-bio.GN