DNMT3A3B

DNMT3A3B is not a standard gene symbol in major genomic databases. In scientific writing, the term is sometimes used informally to refer to the two de novo DNA methyltransferases DNMT3A and DNMT3B together, highlighting their related roles in establishing new DNA methylation patterns during development and differentiation. There is no separate, widely recognized gene called DNMT3A3B as an independent entity.

DNMT3A and DNMT3B are enzymes that catalyze the transfer of a methyl group to cytosine residues in CpG dinucleotides, thereby establishing de novo DNA methylation. They share catalytic methyltransferase domains and possess accessory regions such as a PWWP domain that helps chromatin binding and an ADD domain that interacts with histone marks. Their activity is enhanced by DNMT3L, a regulatory factor that stimulates catalysis and influences genomic targeting. DNMT3A and DNMT3B can function as homodimers or heterodimers and operate in a cell-type- and locus-specific manner, contributing to tissue-specific methylation landscapes.

Biological and clinical relevance is broad. These enzymes are essential for embryonic development, imprinting, and lineage specification. Aberrant DNMT3A or DNMT3B activity is linked to disease: germline or somatic mutations in DNMT3A are associated with hematologic malignancies and overgrowth syndromes, while mutations in DNMT3B cause immunodeficiency with centromeric instability and facial anomalies (ICF syndrome). Epigenetic alterations involving DNMT3A/3B are observed in various cancers. Therapeutically, DNA methyltransferase inhibitors such as azacitidine and decitabine affect these enzymes and are used in certain hematologic conditions.

Note: For precise genetics, use the established symbols DNMT3A and DNMT3B; DNMT3A3B is not a formal gene designation in current nomenclature.