The inositol polyphosphate-5-phosphatase D gene (INPP5D) is a risk-conferring gene for Alzheimer’s disease (AD) specifically expressed in microglia in the brain, and negatively regulates the phosphoinositide 3-kinase pathway controlling cell migration, proliferation, and survival [22, 23]. Here, INPP5D is linked to early-onset autosomal dominant Alzheimer disease.