TREM2 and Dravet syndrome: We therefore examined alleles and genotype frequencies for TREM2 (R47H) C/T mutation, ApoE haplotypes (ApoE,ɛ2,ɛ3, and ɛ4 alleles), Tau (rs 9468, tagging MAPT, H1 versus H2 haplotypes), and HLA-DR (rs3129882 A/G polymorphism) by SNPs analysis to determine allele prevalence in DS (n = 47, Table 1).