KMT2B belongs to the KMT2 gene family and encodes the lysine-specific histone methyltransferase 2B (KMT2B). KMT2B acts in a multiprotein complex which effects gene regulation by epigenetic modification. Specifically, KMT2B places activating methylation signals on histone 3 lysine 4 (H3K4). These functions of the KMT2B complex have been widely known, but so far it has been less clearly understood how this complex impacts on specific genes and cellular signaling pathways and what human disorders may be the result from mutations in KMT2B.

Two papers have now been published that report on de novo dominant KMT2B mutations in a number of children affected by a particular kind of movement disorder, a condition called dystonia. Dystonias are characterized by involuntary muscle movements and contractions which may then result in abnormal posture and disturbed movement sequences. In severe forms of dystonia, the affected individuals are not able to stand or walk independently. It is assumed that the newly identified dystonia gene KMT2B plays a crucial role in the control of voluntary movement.