C9orf72 and Splenomegaly: Interestingly, C9orf72 knockout (KO) mouse models, with mild motor deficits, exhibit a dysregulated immune response, which is characterized by T-cell activation, overproduction of autoantibodies and cytokines, and signs of massive leukocyte infiltration, such as lymphadenopathy and splenomegaly, thus causing the development of a systemic lupus erythematosus-like disease [11].