This study examined three separate Latin American families with frontotemporal dementia (FTD) and found that they all had the same genetic variation (p.H157Y) in the TREM2 gene. Compared to both sporadic FTD cases and healthy controls, the three patients displayed early behavioral changes, worse cognitive impairments, and more severe brain atrophy, particularly in areas where the TREM2 gene is expressed. One case also had motor neuron disease, with extensive TDP-43 type B pathology in the brain. These results suggest that the p.H157Y variation in TREM2 may contribute to FTD, particularly in populations that are underrepresented in research. (By Dr Agustín Ibáñez, https://jmg.bmj.com/content/early/2023/02/22/jmg-2022-108627 )