Abstracts

Rationale: Rasmussen s encephalitis (RE) is a rare chronic inflammatory disease characterized by intractable focal epilepsy, often epilepsia partialis continua, progressing to hemiparesis, cognitive impairment, and unilateral cerebral atrophy. The etiology of RE remains unknown. We have previously reported the occurrence of two rare autoimmune disorders, Behcet s disease and RE, in a father and son respectively, and suggested that patients might be genetically susceptible to developing autoimmune conditions which have been precipitated by separate environmental triggers. Methods: Review of medical charts of four individuals with a dual diagnosis of RE and other autoimmune disorders (AID). Discussion of possible mechanisms of this association.Results: The diagnosis of RE in all four patients was based on previously reported criteria, and was pathologically confirmed in patients 2, 3 and 4. In family 1, a patient with RE onset at 2 years 8 months developed Hashimoto s thyroiditis at 15 years; he also had a brother with Type 1 (autoimmune) diabetes mellitus. In family 2, the patient had RE onset at 3 years 9 months, and developed ulcerative colitis at 10 years 9 months. In family 3, the patient had RE at the age of 6 years, and developed Crohn s disease at age 14. In family 4, the patient had RE onset at 14 years and onset of systemic lupus erythematosus at 31 years. In these four families, the second AID appeared several years after the onset of RE, with a mean interval of 11 years (median 10 years). Conclusions: We suggest that the incidence of a second autoimmune disease in RE patients may be higher than by chance; however, the true frequency and relative risk are unknown. The delay between the appearance of RE and the second autoimmune disease might seem long but in fact the age of onset of these other AID is younger than average. Distinguishing whether the immune system in RE plays a role in causing, or merely responding, to the disease is still open to question. Our observations suggest that there may be a common predisposing factor for the development of autoimmune responses in these patients. There could be a common underlying genetic susceptibility to developing autoimmune conditions; these may then be precipitated by exposure to two different hits, e.g. separate environmental triggers or other susceptibility genes. Further study of the long term evolution of RE patients, as well as detailed family histories, and use of newer molecular techniques such as CGH microarray and whole exome sequencing, are warranted to clarify this.