SMN1 and proximal spinal muscular atrophy: To determine whether GENDULF can be utilized in other diseases, we then applied it to spinal muscular atrophy (SMA), a neuromuscular disorder of variable severity caused by biallelic mutations of the survival motor neuron 1 gene (SMN1) (Lefebvre et al, 1995) and retention of the paralog gene SMN2. A cytosine to thymine nucleotide change in exon 7 of SMN2 leads to frequent exclusion of exon 7 during splicing of SMN2 pre‐mRNAs and thus less functional SMN protein (Monani et al, 1999).