Junctional Epidermolysis Bullosa (JEB) Test

The Veterinary Genetics Laboratory (VGL) is a non-profit, self-supporting unit of the School of Veterinary Medicine at the University of California, Davis. We provide highly accurate genetic testing results and animal forensic services while also contributing to the educational and research mission of the school.

VGL provides animal parentage verification, identification, forensics services, genetic diagnostics, and genetic research for a broad range of domestic species as well as primates and wildlife species.

Junctional epidermolysis bullosa (JEB) is an inherited disease that causes moderate to severe blistering of the skin and mouth epithelia, and sloughing of hooves in newborn foals. This condition is also known as red foot disease, and was previously known as epitheliogenesis imperfecta (EI) in American Saddlebred horses. Affected foals are typically born alive, but soon develop skin lesions at pressure points. The condition worsens with time and the foal eventually succumbs to severe infection or has to be euthanized.

Junctional epidermolysis bullosa across species has been associated with mutations in three genes (LAMA3, LAMB3, LAMC2) that each encode the three subunits of laminin-5, a glycoprotein vital to the integrity of the skin and mucosa. In horses, mutations in LAMA3 and LAMC2 have been shown to result in JEB.

In Belgian Draft horses and derivatives of that breed, a recessive mutation J in the LAMC2 gene (AY082802.1:c.1571_1572insC) was identified as the cause of junctional epidermolysis bullosa. The insertion in LAMC2 results in a premature termination codon and thus a non-functional laminin-5.

Two copies J are required to develop junctional epidermolysis bullosa. Since affected animals do not survive to breeding age, JEB foals are produced by matings between carrier animals. The VGL offers diagnostic DNA tests that detects the known causal variants for JEB. Breeders can reliably use test results to enhance breeding strategies to avoid producing affected foals. Carriers do not need to be removed from the breeding pool. A successful breeding program can use matings of carriers (N/J) to non-carriers (N/N) without the worry of producing an affected foal.