Interestingly, some of these candidate genes (TIMP2, AKT1, MMP9, CST3, SMN1 and SMN2) were previously associated with susceptibility to ALS while the remaining 18 genes (GAA, KIF1A, MC1R, MECP2, ALPL, HSPG2, L1CAM, PLEC, STK11, CSF1, F2, GSTM3, TRAF2, HSPA5, HTT, IL6, LETMD1, SOAT1) represent novel candidate mediators for disease progression. This evidence concerns the gene L1CAM and amyotrophic lateral sclerosis.