Collagen fibril diameter and its relation to cross-linking of collagen in the skin of patients with amyotrophic lateral sclerosis.

The diameter of collagen fibrils and the age-related, stable cross-link, histidinohydroxylysinonorleucine (HHL), of skin tissue (left biceps) were measured and compared in 11 patients with amyotrophic lateral sclerosis (ALS) and 7 controls. In ALS patients, it was found that (1) the diameter of collagen fibrils and the content of HHL were negatively and significantly associated with the duration of illness (r = -0.74, P < 0.01 and r = -0.72, P < 0.02, respectively), and (2) there was an appreciable positive correlation between the diameter of collagen fibrils and the content of HHL (r = 0.73, P < 0.02). These findings were not observed in controls. These suggest there is a close relationship between the decreased amount of HHL and the small diameter of collagen fibrils in ALS.