Linkage of ALS-FTD2 to chromosome 9p21 has been reported and a hexanucleotide GGGGCC repeat expansions in the chromosome 9 open reading frame 72 (C9ORF72) gene has recently been identified as the causal genetic defect of ALS-FTD2[71]. Here, GRN is linked to amyotrophic lateral sclerosis.