The extended haplotype of DS participants who carried the TREM2 R47H mutation was impressive: D7 (male, 37 years old, ApoEɛ3/ɛ3, Tau H2/H2, TREM2C/T, and HLA-DR A/G) was non-demented, whereas D4 was (female, 39 years old, carrying ApoEɛ3/ɛ4, TauH1/H2, TREM2-C/T, and HLA-DR A/A) developed dementia. The gene discussed is TREM2; the disease is Dravet syndrome.