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GJA1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

GJA1 gene

The GJA1 gene provides instructions for making the connexin 43 protein, which is essential for cell-to-cell communication and the development of various tissues throughout the body.

Normal Function

The GJA1 gene provides instructions for making a protein called gap junction alpha-1 protein, commonly known as connexin 43. This protein belongs to a large family of connexin proteins that facilitate cell-to-cell communication by forming channels known as gap junctions on the surface of cells. These junctions allow for the transport of nutrients, charged particles (ions), and small signaling molecules between cells. Connexin 43 is critical for the development and function of tissues including the eyes, skin, bone, ears, and brain, and it plays a key role in coordinating muscle cell contractions in the heart.

Health Conditions Related to Genetic Changes

Craniometaphyseal dysplasia

Variants in the GJA1 gene can cause the autosomal recessive form of craniometaphyseal dysplasia, characterized by thickening of the skull bones and widening of the metaphysis (the end of long bones). The most common variant involves the substitution of the amino acid arginine with glutamine at position 239 (Arg239Gln or R239Q).

Erythrokeratodermia variabilis et progressiva

Variants in GJA1 cause erythrokeratodermia variabilis et progressiva (EKVP) type 3. This skin disorder is characterized by:

  • Abnormally thickened skin (hyperkeratosis)
  • Areas of darker skin (hyperpigmentation)
  • Temporarily reddened patches of skin
  • Potential palmoplantar keratoderma (thick, scaly, calloused skin on palms and soles)

These variants result in an abnormal connexin 43 protein that fails to reach the cell surface.

Oculodentodigital dysplasia

Variants in GJA1 cause oculodentodigital dysplasia, a condition affecting the eyes (oculo-), teeth (dento-), and fingers (digital). These variants lead to proteins that either do not function properly or disrupt the formation of gap junction channels, impairing communication between cells during early development.

Other disorders

  • Isolated syndactyly type III: Characterized by the fusion of the fourth and fifth fingers.
  • Palmoplantar keratoderma and congenital alopecia 1: A condition involving skin problems, absence of hair from birth, and nail abnormalities caused by an altered connexin 43 protein that allows molecules to pass through channels too easily.

Other Names for This Gene

  • connexin 43
  • CX43
  • Cx43α1
  • gap junction protein, alpha 1, 43kDa
  • gap junction protein, alpha-like

Frequently Asked Questions

Yes, depending on the specific mutation, GJA1-related conditions can impact sensory organs. Oculodentodigital dysplasia, for example, can cause eye abnormalities such as microphthalmia (small eyes) or coloboma, which may affect vision. Additionally, some forms of craniometaphyseal dysplasia can lead to hearing loss due to the thickening of the skull bones compressing the auditory nerves. Regular monitoring by an ophthalmologist and audiologist is recommended for patients with known GJA1 variants to detect and manage any changes in vision or hearing early.
The GJA1 gene produces connexin 43, a protein essential for cell-to-cell communication in bone-forming cells. In craniometaphyseal dysplasia, specific mutations (such as R239Q) cause the connexin 43 protein to accumulate abnormally inside the cells rather than reaching the cell surface. This disruption in communication impairs the normal remodeling process of bone, leading to excessive thickening of the skull bones and widening of the ends of long bones, which can compress nearby nerves and affect facial structure.
EKVP type 3 is characterized by transient, reddish patches of skin that may appear and disappear, often triggered by heat or exercise, alongside areas of thickened, scaly skin (hyperkeratosis) and darkened patches (hyperpigmentation). Management is primarily symptomatic and focuses on skin care, including the use of emollients to keep the skin hydrated and keratolytic agents to reduce scaling. Avoiding triggers like extreme temperatures and friction can help minimize the appearance of the red patches.
The form of craniometaphyseal dysplasia caused by GJA1 mutations is typically inherited in an autosomal recessive pattern. This means that an individual must inherit two copies of the mutated gene, one from each parent, to develop the condition. Parents who are carriers usually do not show symptoms. For family planning, genetic counseling is highly recommended to assess the risk of passing the carrier status to future children and to discuss options for prenatal or preimplantation genetic testing.
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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