• all homozygotes die within hours of birth with a hunched posture, tremor and inability to right themselves, consistent with mice homozygous for a complete deletion of the Pcdhg cluster

• at P0 the spinal cord is grossly smaller than normal, with significant cell death, increased cleaved caspase 3 indicative of apoptosis, fewer cells primarily in the ventral spinal cord, astrocytosis, fewer FOXP2 and PAX2 positive ventral interneurons, and clumping of parvalbumin-positive Ia afferent axon terminals around their motor neuron targets in the ventral horn.