Benign Familial Juvenile Epilepsy Lagotto Romagnolo Type (BFJE)
Benign familial juvenile epilepsy is a form of epilepsy specific to occur in 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 its frequency in some breeds even 10 times higher than among humans. In human beings, genetic epilepsies are the most common neurological disorder among children between 2 and 10 years of age, with often remission in adolescence. 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 a research at University of Helsinki. Episodic involuntary skeletal muscle activity with preserved consciousness during episodes has been reported in Boxer puppies and in an adult Bichon Frise.
First clinical symptoms of benign familial juvenile epilepsy occur between age of 5 to 9 weeks. Symptoms are seizures characterized by tremor in whole body (all limbs, body and head), ataxia and stiffness. Seizures can occur at any time of the day: during sleeping or playing and exercise. The frequency of seizures can vary among puppies; the seizures can be daily or weekly. The length of seizures also varies, from few seconds to few minutes. Most of puppies seem conscious during the seizures, while some are even able to walk or eat while experiencing a seizure. Some owners have reported appearance of Benign familial juvenile epilepsy symptoms in adult age of dogs, at age of 1 year, 2 years and older, with no symptoms during puppy’s growing up. Breeders report that all parents of affected puppies were phenotypically normal. Physical examination of affected puppies revealed no abnormalities. Neurological examination, however, revealed abnormalities, such as generalized ataxia, hypermetria, 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. Severity of abnormalities varies among puppies, whereas in more severe conditions puppies experienced ataxia with falling. Pathologic examination revealed that 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 high percentage of the affected gene carriers. 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.
Jokinen et al. (2007.): Benign familial juvenile epilepsy in Lagotto Romagnolo dogs. J Vet Intern Med. 2007 May-Jun; 21(3):464-71.