Mice homozygous for this deletion have ectopic motor neurons that migrate out of the ventral horn and into the motor roots, with more ectopias in the rostral than the caudal end. These ectopic neurons do not express neuropilin 2. Despite the ectopic motor neurons, homozygotes are overtly normal, with normal body size, life span, fertility, gait, grip strength, and general motor activity, and no aberrant phenotypes detected in the Knockout Mouse Phenotyping (KOMP2) assessment performed at The Jackson Laboratory. Although Ntn5 is expressed in boundary cap cells, it is not required for their development as boundary cells are present in homozygotes. The trigeminal nerve is normal, dorsal root ganglia and their sensory inputs into the dorsal spinal cord are normal, and no nociceptive defects were detected by either von Frey or hot plate testing.
