IGHMBP2 and proximal spinal muscular atrophy: Similarly, mutations in MORC2 can cause CMT type 2Z or SMA (Schottmann et al., 2016; Sevilla et al., 2016) and mutations in IGHMBP2 have been shown to cause both CMT type 2S and SMA with respiratory distress type 1 (SMARD1; Supplementary Table 2) (Grohmann et al., 2001; Cottenie et al., 2014; Pedurupillay et al., 2016; Liu et al., 2017a).