Given the robust expression of Cyfip1 within microglial cells and the early emergence of microglial dysmorphism by the age of 6 months in PWS subjects, we generated a specialized Cx3cr1Cre−ERT+/−Cyfip1fl+/−mouse model targeting myeloid cells, including microglia in the brain. The gene discussed is CYFIP1; the disease is Prader-Willi syndrome.