Detecting DNA cytosine methylation using nanopore sequencing

A hidden Markov model (HMM)-based tool enables detection of 5-methylcytosine (5-mC) from single-molecule nanopore-sequencing data generated directly from human genomic DNA without chemical treatment. In nanopore sequencing devices, electrolytic current signals are sensitive to base modifications, such as 5-methylcytosine (5-mC). Here we quantified the strength of this effect for the Oxford Nanopore Technologies MinION sequencer. By using synthetically methylated DNA, we were able to train a hidden Markov model to distinguish 5-mC from unmethylated cytosine. We applied our method to sequence the methylome of human DNA, without requiring special steps for library preparation.