C9ORF72 transcription in heterozygous 311005021Rik (C9ORF72 mouse ortholog) knock-in C57BL/6 mice is highest in neurons of the hippocampus, cerebellum, cortex, brainstem nuclei and striatum, all of which are known to degenerate in ALS and FTD [23]. Here, C9orf72 is linked to frontotemporal dementia.