 Proximal "NF1" promoter/5’ UTR methylation has been analyzed in tissues from NF1 patients, with the idea that reduced transcription as a result of methylation could be a “second hit” mechanism equivalent to a somatic mutation.There are some sites that have been detected to be methylated at a higher frequency in tumor tissues than normal tissues.These sites are mostly within the proximal promoter; however, some are in the 5’ UTR as well and there is a lot of interindividual variability in the cytosine methylation in these regions.