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. The gene discussed is MMP9; the disease is amyotrophic lateral sclerosis.