TREM2 and Hydrocephalus: To qualitatively evaluate whether the TYROBP loss phenocopies the AD-associated TREM2 variants, we utilized immunohistochemical staining in frontal cortex biopsies to assess microglial clustering around the Aβ plaques (Fig. 4A) in one monoallelic TYROBP deletion carrier and ten non-carriers with different APOE genotypes from Kuopio normal pressure hydrocephalus registry, a cohort containing surgical frontal cortex biopsies collected during ventriculoperitoneal shunt placement to treat suspected NPH [16].