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GJB4 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

GJB4 gene

The GJB4 gene encodes a protein called connexin 30.3, which is essential for cell-to-cell communication and skin health.

Normal Function

The GJB4 gene provides instructions for making a protein called gap junction beta 4, more commonly known as connexin 30.3. This protein is part of the connexin family, a group of proteins that form channels called gap junctions on the surface of cells. Gap junctions open and close to regulate the flow of nutrients, charged atoms (ions), and other signaling molecules from one cell to another. They are essential for direct communication between neighboring cells.

Connexin 30.3 is found in several different tissues, including the outermost layer of the skin (the epidermis). This protein appears to play a role in the growth and maturation of epidermal cells.

Health Conditions Related to Genetic Changes

Erythrokeratodermia variabilis et progressiva

At least eight GJB4 gene mutations have been identified in people with erythrokeratodermia variabilis et progressiva (EKVP), a skin disorder characterized by areas of hyperkeratosis, which is abnormally thickened skin, and temporarily reddened patches called erythematous areas. Each of these mutations changes a single protein building block (amino acid) in connexin 30.3. Studies suggest that the abnormal protein can build up in a cell structure called the endoplasmic reticulum (ER), triggering a harmful process known as ER stress. Researchers suspect that ER stress damages cells in the epidermis and leads to their premature death. The mechanisms by which epidermal damage and cell death contribute to hyperkeratosis at erythematous areas are poorly understood.

Other Names for This Gene

  • connexin 30.3
  • connexin-30.3
  • CX30.3
  • CXB4_HUMAN
  • EKV
  • gap junction beta-4 protein
  • gap junction protein, beta 4, 30.3kDa

Frequently Asked Questions

Research is still evolving, but topical or systemic agents that reduce endoplasmic reticulum (ER) stress—such as low‑dose oral retinoids (e.g., acitretin) or topical sirolimus—have shown anecdotal benefit in a few case reports. These therapies aim to improve protein folding and reduce cell death, but they are not curative and must be prescribed and monitored by a dermatologist experienced with genetic skin disorders.
EKVP typically presents with sharply demarcated, thickened (hyperkeratotic) plaques that may alternate with transient, bright red (erythematous) patches. The lesions often appear in the same locations over time and can be present from early childhood. Unlike eczema, there is usually no intense itching, weeping, or response to typical moisturizers and steroid creams. A dermatologist may notice the characteristic “migratory” red patches that resolve, leaving behind persistent thickened skin, prompting genetic evaluation for GJB4 mutations.
EKVP caused by GJB4 mutations follows an autosomal dominant pattern, meaning a single altered copy of the gene can cause disease. Testing options include targeted sequencing of the GJB4 gene or a broader skin‑disorder gene panel performed on a blood sample. If a pathogenic variant is identified in the family, predictive testing can determine whether you carry the same mutation, allowing for early monitoring and counseling. Genetic counseling is recommended before and after testing to discuss implications for family planning.
Flare‑ups are frequently provoked by heat, sweating, friction, emotional stress, or rapid changes in temperature. Keeping the skin cool, avoiding tight clothing, using gentle, fragrance‑free moisturizers, and minimizing prolonged exposure to hot water can reduce episodes. Some patients find that applying a barrier cream before activities that cause sweating (e.g., exercise) helps prevent new erythematous areas.
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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