C9ORF72 has a domain whith polymorphic hexanucleotide repeat (GGGGCC). The C9ORF72-hexanucleotide repeat expansions have been recently identified as genetic markers in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). FTLD-TDP has five subtypes: Sporadic FTLD,GRN mutation FTLD,TARDBP mutation FTLD,VCP mutation FTLD and C9ORF72 mutation FTLD. The C9ORF72 repeat expansions may indicate a worse prognosis in ALS. Human C9ORF72 has some isoforms with MW 54-60 kDa and 25-30 kDa. Mouse C9orf72 has some isoforms with MW 50-60 kDa and 35 kDa.