Indeed, roles for other epigenetic effectors, including histone methylation91,92 and acetylation93–95 marks, have been implicated in the severity of asthma, and a genome-wide association study identified significant histone modifying enzyme (KDM2A, KDM4C, HDAC4, HDAC7 and HDAC9) polymorphisms96,97 in asthma. This evidence concerns the gene KDM4C and asthma.