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1.  Analysis pipelines and packages for Infinium HumanMethylation450 BeadChip (450k) data 
The Illumina HumanMethylation450 BeadChip has become a popular platform for interrogating DNA methylation in epigenome-wide association studies (EWAS) and related projects as well as resource efforts such as the International Cancer Genome Consortium (ICGC) and the International Human Epigenome Consortium (IHEC). This has resulted in an exponential increase of 450k data in recent years and triggered the development of numerous integrated analysis pipelines and stand-alone packages. This review will introduce and discuss the currently most popular pipelines and packages and is particularly aimed at new 450k users.
PMCID: PMC4304832  PMID: 25233806
HumanMethylation450; Epigenetics; Analysis pipelines; EWAS; DNA methylation; 450k BeadChip
2.  Probe Lasso: A novel method to rope in differentially methylated regions with 450K DNA methylation data 
The speed and resolution at which we can scour the genome for DNA methylation changes has improved immeasurably in the last 10 years and the advent of the Illumina 450K BeadChip has made epigenome-wide association studies (EWAS) a reality. The resulting datasets are conveniently formatted to allow easy alignment of significant hits to genes and genetic features, however; methods that parse significant hits into discreet differentially methylated regions (DMRs) remain a challenge to implement. In this paper we present details of a novel DMR caller, the Probe Lasso: a flexible window based approach that gathers neighbouring significant-signals to define clear DMR boundaries for subsequent in-depth analysis. The method is implemented in the R package ChAMP (Morris et al., 2014) and returns sets of DMRs according to user-tuned levels of probe filtering (e.g., inclusion of sex chromosomes, polymorphisms) and probe-lasso size distribution. Using a sub-sample of colon cancer- and healthy colon-samples from TCGA we show that Probe Lasso shifts DMR calling away from just probe-dense regions, and calls a range of DMR sizes ranging from tens-of-bases to tens-of-kilobases in scale. Moreover, using TCGA data we show that Probe Lasso leverages more information from the array and highlights a potential role of hypomethylated transcription factor binding motifs not discoverable using a basic, fixed-window approach.
PMCID: PMC4304833  PMID: 25461817
Differentially methylated regions; DNA methylation; Epigenetics; EWAS; Illumina 450K BeadChip
3.  oxBS-450K: A method for analysing hydroxymethylation using 450K BeadChips 
•A method is presented for 5hmC detection and analysis using Infinium 450K BeadChips.•The oxBS-450K method can discriminate between 5mC and 5hmC in human gDNA•5hmC levels were quantified genome-wide in 3 distinct biological samples.•The reported 5hmC signal was validated using mass spectrometry and pyrosequencing.•The effects of differing amounts of input DNA on final 5hmC call rate are discussed.
DNA methylation analysis has become an integral part of biomedical research. For high-throughput applications such as epigenome-wide association studies, the Infinium HumanMethylation450 (450K) BeadChip is currently the platform of choice. However, BeadChip processing relies on traditional bisulfite (BS) based protocols which cannot discriminate between 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). Here, we report the adaptation of the recently developed oxidative bisulfite (oxBS) chemistry to specifically detect both 5mC and 5hmC in a single workflow using 450K BeadChips, termed oxBS-450K. Supported by validation using mass spectrometry and pyrosequencing, we demonstrate reproducible (R2 > 0.99) detection of 5hmC in human brain tissue using the optimised oxBS-450K protocol described here.
PMCID: PMC4304834  PMID: 25175075
Hydroxymethylation; DNA methylation; 450K BeadChip; Oxidation; Bisulfite conversion; Epigenetics
4.  AutoMeDIP-seq: A high-throughput, whole genome, DNA methylation assay 
Methods (San Diego, Calif.)  2010;52(3-13):223-231.
DNA methylation is an epigenetic mark linking DNA sequence and transcription regulation, and therefore plays an important role in phenotypic plasticity. The ideal whole genome methylation (methylome) assay should be accurate, affordable, high-throughput and agnostic with respect to genomic features. To this end, the methylated DNA immunoprecipitation (MeDIP) assay provides a good balance of these criteria. In this Methods paper, we present AutoMeDIP-seq, a technique that combines an automated MeDIP protocol with library preparation steps for subsequent second-generation sequencing. We assessed recovery of DNA sequences covering a range of CpG densities using in vitro methylated λ-DNA fragments (and their unmethylated counterparts) spiked-in against a background of human genomic DNA. We show that AutoMeDIP is more reliable than manual protocols, shows a linear recovery profile of fragments related to CpG density (R2 = 0.86), and that it is highly specific (>99%). AutoMeDIP-seq offers a competitive approach to high-throughput methylome analysis of medium to large cohorts.
PMCID: PMC2977854  PMID: 20385236
DNA methylation; Automation; Whole genome; High-throughput sequencing; MeDIP

Results 1-4 (4)