The KMT2C gene encodes Lysine-Specific Methyltransferase 2C, a nuclear protein belonging to the myeloid/lymphoid or mixed-lineage leukemia (MLL) family. Similar to all other MLL proteins, KMT2C is activated by a minimized RBBP5–ASH2L heterodimer. The protein functions as an enzyme and is responsible for catalyzing the methylation of the Lysine-4 residue of histone H3. This methylation is necessary for epigenetic transcriptional activation. KMT2C may also function as the catalytic subunit of the MLL2/3 coactivator complex of nuclear receptors, which is involved in transcriptional coactivation.
There have been individual reports of KMT2C gene mutations in patients with Kleefstra Syndrome, a disorder characterized by severe mental retardation, obesity, hypotonia, seizures, microcephaly and facial dysmorphia. However, a direct causal link between this condition and KMT2C mutations has not yet been established.