ANG and amyotrophic lateral sclerosis: To further investigate the relationship between loss of ribonuclease activity and ALS duration, we divided the ANG variants into two categories, variants with less than or equal to ten percent of WT ANG ribonuclease activity and variants with greater than ten percent WT ribonuclease activity and performed Kaplan-Meier analysis (Fig. 5b; note the same results were obtained with a threshold of less than or equal to 20% ribonuclease activity).