However, some important exceptions to these general rules need to be mentioned: a selective spinal signal change in the dorsal columns could be found in patients with acquired dorsal root ganglion alteration (i.e., Sjogren syndrome), and gadolinium enhancement has been reported in some genetic (DARS mutation, Alexander disease, biotinidase deficiency) and acquired (B12 deficiency and methotrexate toxicity) conditions, which can mimic inflammatory conditions (8). This evidence concerns the gene DARS1 and Alexander disease.