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Benign Familial Juvenile Epilepsy (BFJE) Lagotto Romagnolo Type
| Acronym: | BFJE |
| Gene: | LGI2 |
| Mutation: | c.1558A>T |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Benign familial juvenile epilepsy is a form of epilepsy specific to occur in the Lagotto Romagnolo dog breed. Epilepsy is commonly identified in humans, mostly caused by various causes including tumors, trauma, stroke, and neurodegenerative disease, but epilepsy can be also a disease for itself and caused by a genetic mutation. Such genetic epilepsy syndromes are the most common neurological disorders of dogs, with their frequency in some breeds even 10 times higher than among humans. Benign familial juvenile epilepsy in Lagotto Romagnolo is newly identified disordered, with its first report in 2002. The gene causing the disorder has been identified in 2007 as part of research at the University of Helsinki. The first clinical symptoms of benign familial juvenile epilepsy occur between the ages of 5 to 9 weeks. Symptoms are seizures characterized by tremors in the whole body (all limbs, body, and head), ataxia, and stiffness. The frequency and length of seizures can vary among puppies; the seizures can be daily or weekly. Physical examination of affected puppies revealed no abnormalities. Neurological examination, however, revealed abnormalities, such as generalized ataxia, hypermetria, and intention tremor, and that tremor decreased postural reactions in all 4 limbs or in hind limbs only, and bilaterally decreased menace reaction in all dogs. The severity of abnormalities varies among puppies, whereas in more severe conditions puppies experienced ataxia with falling. Pathologic examination revealed that the cerebellum is smaller than usual, which gains only 7% of the total brain weight, while the normal cerebellum is >10%. It was observed also that there is a mild scattered Purkinje cell loss.
Benign familial juvenile epilepsy in Lagotto Romagnolo (BFJE) is caused by a point mutation in the LGI2 gene. Research revealed a high percentage of the affected gene carriers. The research included 576 Lagotto Romagnolo dogs from different countries and a carrier rate was 32%. BFJE is inherited in an autosomal recessive pattern. Healthy parents of an affected dog are obligate heterozygotes and therefore carry one mutant allele. Heterozygotes have no symptoms. At conception, each cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
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:
Jokinen et al. (2007.): Benign familial juvenile epilepsy in Lagotto Romagnolo dogs. J Vet Intern Med. 2007 May-Jun; 21(3):464-71.
Seppala et al. (2011): LGI2 truncation causes a remitting focal epilepsy in dogs. PLoS Genet. 2011 Jul; 7(7):e1002194.