Though the specific mechanisms by which<unk>  acts vary from organism to organism, all well-documented cases point towards epigenetic modification and RNA-silencing as the underlying mechanism for<unk> . In the case of the r1 locus in maize, DNA methylation of a region of tandem repeats near the coding region of the gene is characteristic of the paramutagenic B’ allele, and when the paramutable B-I allele becomes paramutagenic, it too takes on the same DNA methylation pattern. In order for this methylation to be successfully transferred, a number of genes coding for RNA-dependent RNA polymerases and other components of RNA-silencing pathways are required, suggesting that<unk>  is mediated via endogenous RNA-silencing pathways. The transcription of short interfering RNAs from the tandem repeat regions corroborates this. In animal systems such as Drosophila, piRNAs have also been implicated in mediating<unk> . In addition to the characteristic DNA methylation state changes, changes in histone modification patterns in the methylated DNA regions, and/or the requirement of histone modifying proteins to mediate<unk>  have also been noted in multiple systems. It has been suggested that these histone modifications play a role in maintaining the paramutated state. The previously mentioned tandem repeat region in the r1 locus is also typical of other loci showing<unk>  or<unk> -like phenomena. However, it has been noted that it is not possible to explain all occurrences and features of<unk>  with what is known about RNAi-mediated transcriptional silencing, suggesting that other pathways and/or mechanisms are also at play.
Paramutation
Expressivity 
Caudal duplication
Pseudodominance
Bromism
Uniparental disomy
Variegation 
Isodisomy