POU5F1 and proximal spinal muscular atrophy: A landmark early application of iPSC technology in disease modeling focused on spinal muscular atrophy (SMA), a severe inherited neurological disorder with high infant mortality.390 Ebert et al391 reprogrammed fibroblasts from a patient with SMA and an unaffected parent into iPSCs using lentiviral delivery of the transcription factors OCT4, SOX2, NANOG, and LIN28.391 These iPSCs were then differentiated into motor neurons, revealing a reduced number of motor neurons and lower levels of SMA protein in patient-derived cells compared to controls.