PLXND1 and Mobius syndrome: When looking at congenital neuron defects, PLXND1 has been reported in association with classical MBS in a cohort of 12 patients [14], with the same study documenting that in both knockdown (+/−) and knockout (−/−) mice, a subpopulation of motor neurons within the primordial facial nerve area (r4/r5) showed impaired migration (Figure 1B).