Figure 2. Subtle differences in slope estimates were evident across the 3 amyotrophic lateral sclerosis (ALS) cohorts.

Whereas 6 steps were modeled for male Australian patients and 7 steps were evident in female patients, the converse was observed in the Japanese patients with ALS (7 steps for male patients and 6 steps for female patients). In the South Korean patients with ALS, the slope estimates for male and female patients with ALS were similar. Irrespective of the subtle sex differences in slope estimates, the strong linear relationship was maintained, indicating that ALS was a multistep process across the different ethnic populations. Circles, men; squares, women.