TREM2 and frontotemporal dementia: The most common disease-causing alteration is the hexanucleotide repeated expansion (HRE) of the C9ORF72 gene, while the most frequently studied genes are MAPT, GRN, and FUS. In recent years, variants of the TARDBP, SQSTM1, TREM2, CSF1R, and TMEM106B genes have also been described as monogenic and/or disease-modifying factors in FTD [1, 3, 4].