Employing rat and mouse models, we validated that microglial dysmorphism stems from the dysfunctional cytoplasmic Fragile X Messenger Ribonucleoprotein 1 (FMR1) interacting protein 1 (CYFIP1), one of the four additional haploinsufficient genes exclusive to PWS T1 [8]. This evidence concerns the gene CYFIP1 and Prader-Willi syndrome.