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MAP2K1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

MAP2K1 gene

The MAP2K1 gene provides instructions for making the MEK1 protein kinase, which is essential for regulating cell growth, division, and survival.

Normal Function

The MAP2K1 gene provides instructions for making a protein known as MEK1 protein kinase. This protein is part of a signaling pathway called the RAS/MAPK pathway, which transmits chemical signals from outside the cell to the cell's nucleus. RAS/MAPK signaling helps control the growth and division (proliferation) of cells, the process by which cells mature to carry out specific functions (differentiation), cell movement (migration), and the self-destruction of cells (apoptosis). MEK1 protein kinase appears to be essential for normal development before birth and for survival after birth.

Health Conditions Related to Genetic Changes

Cardiofaciocutaneous syndrome

At least 13 mutations in the MAP2K1 gene have been identified in people with cardiofaciocutaneous syndrome. This condition affects many parts of the body, particularly the heart (cardio-), facial features (facio-), and the skin and hair (-cutaneous).

The MAP2K1 gene mutations that cause cardiofaciocutaneous syndrome are germline mutations, which means that they are present in cells throughout the body. Each mutation changes a single protein building block (amino acid) in MEK1 protein kinase. The genetic changes abnormally activate the protein, which disrupts the tightly regulated RAS/MAPK signaling pathway in many types of cells. The altered signaling interferes with the normal development of many organs and tissues, resulting in the characteristic features of cardiofaciocutaneous syndrome.

Melorheostosis

At least three mutations in the MAP2K1 gene have been identified in people with melorheostosis. This rare disease causes the abnormal growth of new bone tissue on the surface of existing bones. The new bone has a characteristic "dripping candle wax" or flowing appearance on x-rays.

The mutations associated with melorheostosis are described as somatic. Somatic mutations occur during a person's lifetime and are present only in certain cells, in this case, bone cells in a particular area of the body. The known mutations change single amino acids in MEK1 protein kinase. The mutations lead to the production of a version of the protein that is overactive, which increases RAS/MAPK signaling in bone tissue. The increased signaling disrupts the regulation of bone cell proliferation and allows new bone to grow abnormally. Studies suggest that increased RAS/MAPK signaling also stimulates excess bone remodeling, a normal process in which old bone is broken down and new bone is created to replace it.

Noonan syndrome with multiple lentigines

At least one mutation in the MAP2K1 gene has been found to cause Noonan syndrome with multiple lentigines (formerly called LEOPARD syndrome). This condition is characterized by multiple brown skin spots (lentigines), heart defects, short stature, a sunken or protruding chest, and distinctive facial features.

The identified MAP2K1 gene mutation is a germline mutation that replaces the amino acid glutamic acid with the amino acid glycine at position 102 (written as Glu102Gly or E102G) in MEK1 protein kinase. This change likely results in increased activation of the RAS/MAPK signaling pathway in cells throughout the body.

Other cancers

Mutations in the MAP2K1 gene have been found in several forms of cancer, including blood cell cancer (leukemia and lymphoma), lung cancer, and a form of skin cancer called melanoma. These are somatic mutations that occur only in the cells that give rise to cancer. The genetic changes lead to an overactive MEK1 protein kinase, which increases activation of the RAS/MAPK signaling pathway, allowing cells to grow and divide too quickly.

Other Names for This Gene

  • Dual Specificity Mitogen-Activated Protein Kinase Kinase 1
  • ERK Activator Kinase 1
  • MAP Kinase Kinase 1
  • MAPK/ERK kinase 1
  • MAPKK1
  • MEK-1
  • MEK-1 Protein Kinase
  • MEK1
  • MKK-1 Protein Kinase
  • MKK1
  • MKK1 Protein Kinase
  • MP2K1_HUMAN
  • PRKMK1
  • protein kinase, mitogen-activated, kinase 1 (MAP kinase kinase 1)

Frequently Asked Questions

MEK inhibitors (e.g., trametinib) have shown promise in small case series by reducing MAPK pathway hyperactivity and slowing new bone formation. Treatment is off‑label and usually considered when pain, functional limitation, or progressive deformity is severe; it requires close monitoring for skin rash, cardiac effects, and laboratory abnormalities.
Explain that MAP2K1 CFC syndrome is autosomal dominant; each child has a 50% chance of inheriting the mutation. Discuss options such as pre‑implantation genetic testing (PGT‑M) with IVF, prenatal diagnostic testing (CVS/amniocentesis), or use of donor gametes. Emphasize that phenotype can vary, even within families.
Baseline echocardiogram and electrocardiogram should be performed at diagnosis. Follow‑up imaging is typically recommended every 6‑12 months, or sooner if symptoms (e.g., shortness of breath, chest pain, murmur) develop, to monitor for hypertrophic cardiomyopathy, septal defects, or valve abnormalities common in CFC.
Patients often have ichthyosis‑like dry scaling, hyperkeratotic plaques, and sparse, curly hair. Emollients with ceramides, topical retinoids for hyperkeratosis, and occasional keratolytic agents (e.g., urea 10‑20%) can improve texture. Dermatology referral is advised for persistent or severe lesions.
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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