PDCD1 and autism spectrum disorder: The clinical similarities are remarkable, with patients with schizophrenia exhibiting both microglial activation and aberrant frontostriatal myelin, whereas genetic studies have implicated BMP pathway dysregulation in autism spectrum disorder susceptibility.[64, 65] Our findings position endothelial PD‐1 as a critical integrator of vascular and gliogenic signaling, where its loss disrupts the coordination between angiogenesis and myelination programs.