While our custom-designed RXDX-106 datasheet array included 998 sites from the X chromosome and several thousand sites

from autosomal chromosomes, only X chromosome sites were found to be consistently hypermethylated (n = 18) or hypomethylated (n = 25) in twins with SSc while sharing identical methylation profiles in the one set concordant for the disease. These sites corresponded to 26 genes that were investigated further for their function and their putative pathways involved; such genes could be expected to be expressed differentially based on their methylation profile although an inverse correlation between hypermethylation and reduced expression can only be hypothesized and should be investigated by reverse transcription–polymerase chain reaction (RT–PCR) in the future if additional blood samples can be obtained for this purpose. Among differentially

methylated selleckchem sites, we found some of particular interest. First, the spermine synthase (SMS) gene encodes for an enzyme involved in polyamine synthesis and recycling [39]. The synthesis is directed by two aminopropyltransferases, i.e. spermidine synthases converting putrescine into spermidine and SMS which converts spermidine into spermine, with decarboxylated S-adenosylmethionine (SAM) as the aminopropyl donor in both cases [40]. A ‘polyamine hypothesis’ has been proposed recently by Wesley Brooks, who

suggests that alterations in polyamine synthesis may lead to disease phenotype secondary to abnormalities in DNA methylation status when SAM is in excess [41]. Secondly, among hypomethylated sites, four refer to the gene encoding for DDX26B, a member of the DEAD/H-box helicases involved in various steps of RNA metabolism and chromatin dynamics [42,43], particularly in the Drosophila Meloxicam mode [44]. Of note, DDX proteins are involved in virus-induced innate immunity acting as a scaffold for protein–protein interactions in the signalling cascade that controls IFN type 1 [45] as a critical component of the TANK-binding kinase-1 that activates the transcription factor IFN regulatory factor (IRF)-1 and IRF-7 to promote the expression of IFN-α and -β[46]. Accordingly, changes in DDX3X expression mediated by altered methylation may support the correlation between viral infections and SSc [47]. Thirdly, the association between SSc and ENOX2 hypomethylation is of particular interest, as tissue hypoxia is a major feature of SSc tissues. ENOX2 is a membrane copper-containing enzyme that catalyzes electron transfer from hydroquinone or nicotinamide adenine dinucleotide (NADH) to molecular oxygen, thus playing a role in the induction of reactive oxygen species [48] which have a direct profibrogenic effects on fibroblasts, thus favouring fibrosis [49].