A syndrome that is characterized by progressive presenile dementia and recurrent bone fractures due to polycystic osseous lesions of the lower and upper extremities that has_material_basis_in homozygous mutation in the TYRO protein tyrosine kinase binding protein (TYROBP) gene on chromosome 19q13 or homozygous mutation in the triggering receptor expressed on myeloid cells 2 (TREM2) gene on chromosome 6p21.