Spinal muscular atrophy (SMA) is a recessive neuromuscular disease that is caused by loss-of-function mutations in the survival motor neuron 1 (SMN1) gene and is one of the most common inheritable causes of infant death, where without immediate treatment, infants succumb to respiratory insufficiency within the first years of life. Disease penetrance can inversely correlate with copy number of the paralog gene SMN2 – which can vary from 2 to 5 copies in most individuals – depending on sufficiency in the levels of functional full-length SMN proteins being produced, which is a very small minority from SMN2 mRNA that make it as full-length transcripts that include exon 7.