B2M and amyotrophic lateral sclerosis: Genes presented in 40 and 80 days lists are mostly related to major histocompatibility complex (MHC) class I (H2-Bl, H2-K1, H2-Q1, H2-Q10, H2-Q2, H2-Q7, H2-T22, H2-T23—80 days ALS mice), molecules necessary for peptide loading (Tap2—80 days ALS mice) and to surface expression (B2m—40 days ALS mice) (Kimura and Griffin, 2000).