Gene duplications in AT-1/SLC33A1 have been identified in patients with autistic-like features, intellectual disability, and dysmorphic features; heterozygous mutations in AT-1/SLC33A1 are associated with a familial form of spastic paraplegia, while homozygous mutations are associated with developmental delay and premature death3–7. This evidence concerns the gene SLC33A1 and Spastic paraplegia.