ARHGEF28 and frontotemporal dementia: Patient 2 is a male of French descent, who presented with spinal disease onset at 42 years of age, had no evidence of cognitive decline or frontotemporal dementia, and was negative for the C9orf72 hexanucleotide (G4C2) expansion or for variants in any of the known ALS genes evaluated (ALS2, ANG, ARHGEF28, ATXN2, C21orf2, CENPV, CHMP2B, DAO, DCTN1, FIG4, FUS, GRN, HNRNPA1, HNRNPA2B1, MAPT, MATR3, NEFH, NEK1, OPTN, PFN1, PNPLA6, PRPH, SETX, SIGMAR1, SOD1, SQSTM1, TAF15, TARDBP, TBK1, TUBA4A, UBQLN2, UNC13A, VAPB, and VCP).