DNA (cytosine-5)-methyltransferase 3A is an enzyme that catalyzes the transfer of methyl groups to specific CpG structures in DNA, a process called DNA methylation. The enzyme is encoded in humans by the DNMT3A gene. This enzyme is responsible for de novo DNA methylation. Such function is to be distinguished from maintenance DNA methylation which ensures the fidelity of replication of inherited epigenetic patterns. DNMT3A forms part of the family of DNA methyltransferase enzymes, which consists of the protagonists DNMT1, DNMT3A and DNMT3B. While de novo DNA methylation modifies the information passed on by the parent to the progeny, it enables key epigenetic modifications essential for processes such as cellular differentiation and embryonic development, transcriptional regulation, heterochromatin formation, X-inactivation, imprinting and genome stability. DNMT3a is the gene most commonly found mutated in clonal hematopoiesis, a common aging-related phenomenon in which hematopoietic stem cells (HSCs) or other early blood cell progenitors contribute to the formation of a genetically distinct subpopulation of blood cells. From Wikipedia