These trangenic mice demonstrate reduced brain E2 concentrations, early-onset and increased brain production and deposition of Aβ plaques.Microglial culture from these mice show impaired ability to clear and degrade Aβ plaques.Such plaque abnormalities not found in OVX APP23 mice, suggesting brain aromatase deficiency/estrogen depletion as being an important determinant for developing AD-associated neuropathologies. The gene discussed is CYP19A1; the disease is Alzheimer disease.