The mouse C9ORF72 ortholog is enriched in neurons known to degenerate in ALS and FTD

Using transgenic mice harboring a targeted LacZ insertion, we studied the expression pattern of the C90RF72 mouse ortholog (3110043021Rik). Unlike most genes that are mutated in amyotrophic lateral sclerosis (ALS), which are ubiquitously expressed, the C90RF72 ortholog was most highly transcribed in the neuronal populations that are sensitive to degeneration in ALS and frontotemporal dementia. Thus, our results provide a potential explanation for the cell type specificity of neuronal degeneration caused by C90RF72 mutations.