SIGMAR1 and X-linked distal spinal muscular atrophy type 3: The only affected family member, the younger sister, suffers from polyneuropathy, most likely an autosomal recessive distal spinal muscular atrophy (DSMA2; OMIM#605726) with an identified likely pathogenic sigma non-opioid intracellular receptor 1 (SIGMAR1) variant in a homozygous state, which is in line with clinical, molecular and genealogical findings in the patient/family (Figure 1).