UBQLN2 and frontotemporal dementia: In addition to the common MAPT, GRN, C9orf72, CHCHD10, VCP, and TBK1 genes, we also focus on some rare FTD-related genes, including the CHMP2B, TARDBP, SQSTM1, FUS, UBQLN2, OPTN, TREM2, CYLD, PRKAR1B, TIA1, TUBA4A, CCNF, DCTN1, HNRNPA2B1, and HNRNPA1. Furthermore, we aim to illustrate the phenotypic characteristics of the FTD-gene mutation carriers.