In recent years long non-coding (lnc) RNAs have been revealed as epigenetic regulators that can target activation or silencing to single genes or broader chromosomal domains. Among the best-characterized lncRNAs are imprinted lncRNAs that initiate silencing of a cluster of genes. In the Igf2r imprinted cluster the lncRNA Airn causes silencing of the antisense overlapped Igf2r gene and the non-overlapped Slc22a2 and Slc22a3 genes whose promoters lie 159 and 234kb upstream of the Airn transcription start site. We have recently shown that Airn silences Igf2r by transcription interference with its promoter, a well-characterized gene regulation mechanism in bacteria and yeast. This work identified a novel mechanism for lncRNA mediated gene silencing whereby transcription alone causes silencing and the RNA product plays no role. In contrast, published evidence indicates that Airn acts by a different mechanism to silence Slc22a3, with the Airn lncRNA product targeting the repressive EHMT2 H3K9dimethyltransferase to the Slc22a3 promoter to cause silencing. We detect 3C interactions between the Slc22a2 and Slc22a3 promoters and elements within the Airn gene only on the maternal allele where Airn is not expressed. Some of these same elements within Airn show maternal allele enrichment for enhancer marks. This data supports an alternative model whereby Airn silences Slc22a2 and Slc22a3 by transcriptional interference with enhancers, an entirely novel mechanism of gene regulation. To test this hypothesis we are currently generating a deletion of Airn on the maternal allele taking a chromosome engineering approach using existing loxP sites.