LAMB3 gene
The LAMB3 gene provides essential instructions for creating a component of laminin 332, a protein critical for skin integrity and wound healing.
Overview
The LAMB3 gene provides instructions for making one part (subunit) of a protein called laminin 332 (formerly known as laminin 5). This protein is composed of three subunits: alpha, beta, and gamma. While the LAMB3 gene carries the instructions for the beta subunit, the alpha and gamma subunits are produced from other genes.
Laminins are a group of proteins that regulate cell growth, motility, and adhesion. They are vital for the formation and organization of basement membranes—thin, sheet-like structures that support and separate cells in many tissues. Laminin 332 plays a particularly important role in the basement membrane underlying the epidermis (the top layer of skin). It provides strength and resiliency to the skin and acts as a barrier between the body and the environment. It is a major component of anchoring filaments, which connect the layers of the basement membrane to hold the skin together.
Research suggests laminin 332 is also important for wound healing, the development of tooth enamel, and the function of the cornea (the clear outer covering of the eye).
Health Conditions Related to Genetic Changes
Junctional epidermolysis bullosa (JEB)
More than 100 mutations in the LAMB3 gene have been identified in individuals with junctional epidermolysis bullosa (JEB). This condition involves the following forms:
- JEB generalized severe: Usually results from mutations that prevent the production of functional laminin 332, often due to a premature stop signal in the gene instructions. Without this protein, the epidermis is only weakly connected to underlying skin layers. Minor trauma, such as rubbing or scratching, causes the layers to separate and form blisters. Infants with this form develop widespread, life-threatening blistering.
- JEB generalized intermediate: Caused by mutations that alter, add, or delete small numbers of amino acids, or change how the gene instructions are processed. These mutations typically allow for the production of laminin 332 that retains some function. Blistering may be limited to the hands, feet, knees, and elbows and often improves after the newborn period.
Amelogenesis imperfecta
The LAMB3 gene is also associated with amelogenesis imperfecta, a condition affecting the development of tooth enamel.
Genomic Location
The LAMB3 gene is found on chromosome 1.