Both compound heterozygous patients with SMN1 point variant were female, classified as SMA type I, and had two copies of SMN2. Since patients with two copies of SMN2 most often are classified as SMA type I (Calucho et al., 2018), it is unclear whether this rare variant is linked to a more severe phenotype. This evidence concerns the gene SMN1 and spinal muscular atrophy, type 1.