Other genes encoding subunits of the exosome complex, EXOSC3 and EXOSC8, were also described to cause PCH, spinal muscular atrophy (SMA) and central nervous system demyelination.1 Moreover, a homozygous missense variant in the RBM7, a co-factor of the exosome complex, was shown in an infant with a progressive disease course resulting in death (Table 1, Supplementary Table 1). Here, EXOSC3 is linked to proximal spinal muscular atrophy.