ATL1 and hereditary spastic paraplegia: Three HSP patients (including two siblings) were characterized by a genetic point mutation in, respectively, exon 12 (c.1483C > T; p.Arg495Trp) and exon 8 (two siblings; c.757G > A; p.Val253Ile) of the SPG3a (ATL1) gene, resulting in a mutated ATLASTIN 1 protein.