Analyzing DNA-Immunoprecipitation Sequencing Data.

Genome-wide profiling of DNA modifications has advanced our understanding of epigenetics in mammalian biology. Whereas several different methods for profiling DNA modifications have been developed over the last decade, DNA-immunoprecipitation coupled with high-throughput sequencing (DIP-seq) has proven a particularly adaptable and cost-effective approach. DIP-seq was especially valuable in initial studies of the more recently discovered DNA modifications, 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine. As an enrichment-based profiling method, analysis of DIP-seq data poses several unique, and often unappreciated bioinformatics challenges, which if unmet, can profoundly affect the results and conclusions drawn from the data. Here, we outline key considerations in both the design of DIP-seq assays and analysis of DIP-seq data to ensure the accuracy and reproducibility of DIP-seq based studies.