Prototype human NSCs (HFB2050) secrete a spectrum of NTFs, including BDNF and GDNF [14], whereas genetically engineered NPCs may produce high levels of one specific NTF only, which may not be adequate to counteract ALS pathophysiology that is triggered by multiple pathogenic pathways [141]. The gene discussed is BDNF; the disease is amyotrophic lateral sclerosis.