Reduced CCR2+ PBMCs in peripheral blood at the time of sample collection may raise the possibility of their migration and extravasation in CNS through damaged blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB) in ALS pathogenesis [26], [27], [28], [29], however, anatomical and histopathological analysis of BBB and BSCB was not conducted. Here, CCR2 is linked to amyotrophic lateral sclerosis.