HLA Typing in Amyotrophic Lateral Sclerosis

To the Editor.—  Several reports, most recently by Bartfeld et al,¹ indicate possible HLA system involvement in amyotrophic lateral sclerosis (ALS). For example, Bartfeld and co-workers¹ found a trend toward increased frequency of HLA-Bw35, in agreement with Kott et al.² What has not been emphasized is that statistical trends are not important when other studies find different trends. For example, Antel et al³ found increases of HLA-A3 in rapidly progressive ALS and HLA-Bw12 in ALS with slower courses. Kott et al² also found a significant increase in HLA-A3; they stated that their HLA-Bw35 increase was not significant. Jokelainen et al⁴ found an increased incidence of HLA-Bw40 in ALS cases with slower courses. Behan and colleagues⁵ report