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Junctional Epidermolysis Bullosa 1 (JEB1)
| Acronym: | JEB1 |
| Gene: | LAMC2 |
| Mutation: | c.1368insC |
| Inheritance: | Autosomal Recessive |
| Sample type: | WBE (Whole Blood EDTA), HA (Hairs - with roots) |
Genetics and characteristics
Junctional epidermolysis bullosa (JEB1) is a genetic disease also known by the name Red foot disease and Hairless foal syndrome. It is characterized by the lack of intercellular membrane adhesion molecules responsible for skin adhesion, consequently, horses diagnosed with JEB cannot have their skin stay up onto their body. Symptoms of JEB are the formation of splits and skin lesions often found on legs and pressure points sometimes followed by additional skin infections. There are two mutations in horses responsible for JEB, a mutation in the gene for laminin subunit gamma 2 (LAMC2) and a mutation in the gene for laminin subunit alpha 3 (LAMA3). Both mutations encompass subunits of the laminin protein complex, glycoproteins responsible for the complex interaction between cell membranes. Type 1 of JEB is a consequence of a mutation within the LAMC2 gene and it affects draft horses such as Belgian horses, Trait Breton and Trait Comtois. There is no treatment for JEB, skin condition usually gets worse over time and horses soon die from infections caused by skin lesions, or euthanasia is performed due to their extreme pain.
This type of Junctional epidermolysis bullosa found in horses is inherited as an autosomal recessive pattern or mode of inheritance. That means horses that carry two mutated genes will develop the disease, and horses carrying only one mutated gene will be healthy but act as carriers. Horses that carry that specific mutation are more prone to developing this severe disease. Early genetic testing can help identify the carriers and help breeders in the proper selection of future mating pairs.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Cappelli K., Brachelente C., Passamonti F., Flati A., Silvestrelli M., Capomaccio S. (2015). First report of junctional epidermolysis bullosa (JEB) in the Italian draft horse. BMC Vet Res. 11(1):2-5. doi:10.1186/s12917-015-0374-0
Milenkovic, D., Chaffaux, S., Taourit, S., Guérin, G. (2003). A mutation in the LAMC2 gene causes the Herlitz junctional epidermolysis bullosa (H-JEB) in two French draft horse breeds. Genetics, selection, evolution : GSE, 35(2), 249–256. https://doi.org/10.1186/1297-9686-35-2-249
Johnson, G. C., Kohn, C. W., Johnson, C. W., Garry, F., Scott, D., Martin, S. (1988). Ultrastructure of junctional epidermolysis bullosa in Belgian foals. Journal of comparative pathology, 99(3), 329–336. https://doi.org/10.1016/0021-9975(88)90053-9