NDN (necdin, MAGE family member) is a maternally imprinted, paternally expressed tumor suppressor gene located in the Prader-Willi syndrome (PWS) chr15 region (15q11-13) 1. NDN functions as a growth suppressor that facilitates cell cycle arrest by binding to and repressing cell-cycle-promoting proteins, similar to retinoblastoma protein, and interacts additively with p53 to inhibit cell growth 2. The gene exhibits tissue-specific and imprinted epigenetic modifications, including maternal allele-specific DNA hypermethylation of the promoter CpG island and paternal allele-specific histone hyperacetylation correlating with transcriptional activity 3. NDN expression is restricted to post-mitotic neurons in brain tissue and is highest in the hypothalamus during puberty, suggesting a role in puberty timing 4. In ovarian cancers, NDN is dramatically downregulated in 73% of cases through both genetic (loss of heterozygosity in 28% of informative cases) and epigenetic mechanisms (promoter hypermethylation in 23-30% of cancers) 2. Re-expression of NDN decreases Bcl-2 levels, induces apoptosis, inhibits cell growth and migration by deactivating Src, FAK, and RhoA 2. Recent evidence suggests NDN may contribute to PWS pathogenesis when deleted alongside MAGEL2 and MKRN3 5, though individual gene contributions remain incompletely understood.