C9orf72 and Cervical lymphadenopathy: As the C9orf72-null rats exhibited splenomegaly and cervical lymphadenopathy (Figure 1C, D; Figure S1D, E), which is commonly associated with diseases such as chronic lymphocytic leukemia 43, we investigated the expression of immune receptor and inflammatory cytokine genes using RNA-seq, RT-PCR and RT-qPCR assays.