Butterfly effect: Disabling the ATRX gene in forebrain excitatory neurons during embryogenesis alters brain size, structure and connectivity in adult mice, according to a new preprint. Previous work has shown that this intervention induces autism-like behaviors and thus appears to model ATR-X syndrome in people. ATRX-deficient mice of both sexes were smaller than controls, but only male mice showed reduced brain size. Some brain regions—the hippocampus, cerebellum and associated fiber tracts—were smaller in volume in the treated mice, whereas others—the caudal caudate, thalamus, striatum and midbrain—had larger volumes. That a restricted intervention causes such widespread effects, the authors write, suggests a disruption of “the coordinated development of interconnected brain regions.” bioRxiv