Pathogenic mutations in EXOSC3 with PCH 1B (OMIM # 614678) are described by severe muscle weakness, axial hypotonia, spasticity, tongue fasciculations, contractures, marked psychomotor retardation, and axonal motor neuropathy similar to spinal muscular atrophy (SMA) [1, 2, 7]. The gene discussed is EXOSC3; the disease is proximal spinal muscular atrophy.