In a study conducted by Kihira et al., eight individuals with amyotrophic lateral sclerosis were compared to nine control cases. The results indicated that the total number of neurons in Onuf's nucleus in patients with amyotrophic lateral sclerosis did not differ from the control patients. However, normal neurons decreased in number while atrophic neurons increased. It was also shown that the decrease in the number of normal neurons was not due to aging. Patients with amyotrophic lateral sclerosis also contain less RNA in their motoneurons than normal individuals. The decrease in RNA is correlated with the decrease in size of the nucleolus. Thus, the size of the nucleolus may be an early indicator of amyotrophic lateral sclerosis.