In the present study, the patients with PMA were mostly male and rarely had onset in the bulbar region, as previously reported.13,14 Nonetheless, several studies of clinical PMA cases revealed UMN abnormalities at autopsy.37, –, 39 Moreover, a recent study reported that TAR DNA-binding protein 43 kDa pathology in the motor cortices or the hippocampus was common in both clinical ALS and PMA cases, suggesting that PMA is pathologically linked to ALS.40 The present study provides immunologic evidence that PMA and ALS are linked to each other. This evidence concerns the gene TARDBP and amyotrophic lateral sclerosis.