Moreover, cultures of embryonic striatal neurons isolated from Npc1 mutant mice show reduced signaling of BDNF, via the loss of activation of its high-affinity TrkB receptor [17], while the BDNF and TrkB null mice show severe phenotype and exhibit ataxia [18–22] and the selective reduction of cerebellar BDNF expression has been described in ataxic stargazer and waggler mice [21, 23, 24]. The gene discussed is BDNF; the disease is cerebellar ataxia.