An immunohistochemical study of ubiquitin in the skin of sporadic amyotrophic lateral sclerosis

Ubiquitin (UB)-immunoreactive filamentous inclusions, absent in normal cases and in any other disorder, have been found in patients with amyotrophic lateral sclerosis (ALS) and it has been suggested that they may be characteristic of this disorder. However, there has been no study of UB in ALS skin. We made a quantitative immunohistochemical study of the expression of UB in the skin from 19 patients with sporadic ALS and 19 control subjects. The proportion of UB-positive (UB+) cells in the epidermis in ALS patients was significantly higher (p < 0.001) than in controls. There was a significant positive relationship (r = 0.92, p < 0.001) between the proportion and duration of illness in ALS patients. The optical density of UB+ cells in the epidermis in ALS patients is markedly stronger (p < 0.001) than in controls. There was a significant positive relation (r = 0.58, p < 0.01) between the immunoreactivity and duration of illness in ALS patients. These data suggest that changes of UB in ALS skin are related to the disease process and that metabolic alterations of UB may take place in the skin of patients with ALS.