Prior to exome sequencing, coding regions of common dominant HSP genes had been analyzed by Sanger sequencing, including SPAST (spastin) linked to autosomal dominant SPG4 (MIM# 18601) and ATL1 (atlastin) causing SPG3A (MIM# 182600), genes that account for 37-46 % and 6-11 % of dominant HSP cases [25]. Here, ATL1 is linked to hereditary spastic paraplegia.