In summary, this study identified the monoallelic 5.2-kb TYROBP deletion as a novel risk factor which lowers the onset age of AD and dementia, demonstrated for the first time NHD-like bone cysts in a monoallelic TYROBP deletion carrier, and provided insights into key biological pathways altered in microglia-like cells due to TYROBP deletion. The gene discussed is TYROBP; the disease is dementia.