The following keywords have been used: parathyroid tumorigenesis; parathyroid tumors; multiple endocrine neoplasia type 1 syndrome (MEN1); MEN1 gene; allelic loss; loss of heterozygosity; MEN1 parathyroid tumors; tumor suppressor genes; oncogenes; epigenetics; oncomir; microRNAs/miRNAs. This evidence concerns the gene MEN1 and multiple endocrine neoplasia type 1.