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KMT2D gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

KMT2D gene

The KMT2D gene provides instructions for making an enzyme that regulates gene activity through histone modification and is essential for normal development.

Normal Function

The KMT2D gene, also known as MLL2, provides instructions for making an enzyme called lysine-specific methyltransferase 2D that is found in many organs and tissues of the body. Lysine-specific methyltransferase 2D functions as a histone methyltransferase. Histone methyltransferases are enzymes that modify proteins called histones. Histones are structural proteins that attach (bind) to DNA and give chromosomes their shape. By adding a molecule called a methyl group to histones (a process called methylation), histone methyltransferases control (regulate) the activity of certain genes. Lysine-specific methyltransferase 2D appears to activate certain genes that are important for development.

Lysine-specific methyltransferase 2D is also believed to act as a tumor suppressor, which means it normally helps prevent cells from growing and dividing in an uncontrolled way.

Health Conditions Related to Genetic Changes

Cancers

Some gene variants occur during a person's lifetime. Such changes, which are called somatic variants, are present only in certain cells. Somatic variants in the KMT2D gene have been identified in certain cancers, including medulloblastomas (cancerous brain tumors in childhood) and blood-related cancers called lymphomas. Most of these variants result in an abnormally short, nonfunctional enzyme that cannot perform its role as a tumor suppressor.

Increased amounts of lysine-specific methyltransferase 2D and altered distribution of the enzyme within cells have been identified in cancerous tumors of the breast and colon. Excess amounts of this enzyme may disrupt the regulation of other genes, causing cells to grow and divide too quickly or in an uncontrolled way.

Kabuki syndrome

Hundreds of variants in the KMT2D gene have been identified in people with Kabuki syndrome, a disorder characterized by distinctive facial features, intellectual disability, and abnormalities affecting other parts of the body.

  • The variants change one building block (amino acid) in the enzyme, delete genetic material, or result in a premature stop signal.
  • These changes result in a nonfunctional enzyme, which disrupts histone methylation and impairs the activation of genes necessary for normal development.
  • Although the enzyme is believed to be a tumor suppressor, a loss of its function does not seem to increase cancer risk in people with Kabuki syndrome.

Other Names for This Gene

  • AAD10
  • ALL1-related protein
  • ALR
  • CAGL114
  • histone-lysine N-methyltransferase MLL2
  • KMT2B
  • lysine (K)-specific methyltransferase 2D
  • lysine N-methyltransferase 2B
  • MLL2
  • MLL2_HUMAN
  • MLL4
  • myeloid/lymphoid or mixed-lineage leukemia 2
  • TNRC21
  • trinucleotide repeat containing 21

Frequently Asked Questions

There is no cure that reverses the genetic defect, but early intervention with speech therapy, occupational therapy, and individualized education plans can significantly improve functional outcomes. Some patients benefit from targeted medications for associated conditions (e.g., antiepileptic drugs for seizures). Regular monitoring by a multidisciplinary team helps address emerging health issues promptly.===
Somatic mutations that truncate or reduce KMT2D function can disrupt normal gene regulation, leading to uncontrolled cell growth. Adults with Kabuki syndrome have a higher incidence of skin cancers, breast cancer, and certain lymphomas. While no universal guideline exists, many clinicians recommend age-appropriate cancer screenings (e.g., mammograms, skin exams, colonoscopies) and a lower threshold for investigating unexplained masses or lesions.
Children with KMT2D mutations often have distinctive facial features such as arched eyebrows, long palpebral fissures, a broad nasal tip, and a slightly cleft or depressed nasal bridge. They may also have mild to moderate developmental delays, speech difficulties, and sometimes heart or kidney anomalies. A combination of these signs prompts clinicians to order genetic testing for KMT2D.
KMT2D mutations are usually inherited in an autosomal dominant pattern. If a parent carries a pathogenic variant, each child has a 50 % chance of inheriting it. However, many cases arise de novo (new in the child), so a normal test in a parent does not completely rule out a risk for future children. Genetic counseling is recommended before family planning.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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