MECP2 and atypical Rett syndrome: Microglia from the Mecp2-null mice exhibit profoundly impaired phagocytic ability compared with wild-type microglia, suggesting that insufficient clearance of debris from the brain of these animals may contribute to developmental disorders; phagocytosis, the mechanism for clearance of both self and foreign cellular material, is critical to normal brain development and function, and an imbalance in this process of clearance and regeneration may contribute to several developmental abnormalities observed in ASD and Rett syndrome [1].