Because we see phenotypes cluster with smn1, gemin3, and gemin5, it is possible that a fraction of undiagnosed SMA cases or related neurodegenerative diseases could be caused by variants in either GEMIN3 or GEMIN5. It is also possible that the functions of the three SMN complex members outside of snRNP assembly are somehow linked to SMA pathology and deficient regeneration is an underlying mechanism for SMA and even for other neurological diseases. This evidence concerns the gene DDX20 and nervous system disorder.