Retrotransposons (transposable elements) are retroviral particles that are present in large numbers in the genome of plants and animals. They can either activate or switch off the activity of neighbouring genes by demethylation or methylation.
A transposon (colloquially jumping gene) is a segment of DNA in the genome that can change its position in the genome (transposition). Retrotransposons are transposons that use RNA as a mobile intermediate.
In contrast, DNA transposons are also called class I transposons, which do not require RNA as an intermediate.
Sometimes retrotransposons can be released from DNA and reinserted at another integration site ("jumping genes"). In several dog breeds, a mutation under the control of a retrotransposon causes a brindle coat pattern that corresponds to human Blaschko lines .