Interestingly, recessive mutations in prereplication complex (pre-RC) genes, including ORC1, ORC4, ORC6, CDT1, CDC6, and CDC45, have been reported to be involved in MGS (Bicknell et al., 2011), suggesting that factors involved in DNA replication initiation play a role in suppressing MGS symptoms. This evidence concerns the gene ORC4 and Mungan syndrome.