Heterozygous variants in TREM2 are known to be a risk factor for Alzheimer’s disease (Guerreiro et al., 2013) and levels of the TREM2 protein have been shown to be abnormal in FTD (Heywood et al., 2018; Woollacott et al., 2018). The gene discussed is TREM2; the disease is early-onset autosomal dominant Alzheimer disease.