DNMT3B（DNA methyltransferase 3 beta），癌症关联基因，基因ID：1789，cpg甲基化是一种表观遗传修饰，对胚胎发育、印记和x染色体失活具有重要意义。在老鼠身上的研究表明，哺乳动物的发育需要dna甲基化。这个基因编码一个dna甲基转移酶，它被认为在新甲基化中起作用，而不是维持甲基化。该蛋白主要定位于细胞核，其表达受发育调控。该基因突变导致免疫缺陷着丝粒不稳定面部畸形（icf）综合征。已经描述了八个选择性剪接的转录变体。变异体4和5的全长序列尚未确定。[由RefSeq提供，2011年5月]CpG methylation is an epigenetic modification that is important for embryonic development， imprinting， and X-chromosome inactivation. Studies in mice have demonstrated that DNA methylation is required for mammalian development. This gene encodes a DNA methyltransferase which is thought to function in de novo methylation， rather than maintenance methylation. The protein localizes primarily to the nucleus and its expression is developmentally regulated. Mutations in this gene cause the immunodeficiency-centromeric instability-facial anomalies (ICF) syndrome. Eight alternatively spliced transcript variants have been described. The full length sequences of variants 4 and 5 have not。