Heterozygous rare variants in TREM2 are associated with increased risk for neurodegenerative diseases (NDDs), including Alzheimer’s disease (AD), Parkinson’s disease (PD), frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) [9,10,11,12,13]. Here, TREM2 is linked to early-onset autosomal dominant Alzheimer disease.