2012). Different mutations in the same gene can cause either pure or complex FSP, and intrafamilial phenotypic variability is high, greatly complicating the genetic diagnosis of FSP. Seventy-one forms of FSP (SPG1 to SPG48) have been described involving many gene loci (Novarino et al. 2014), with 20 or more loci associated with autosomal dominant FSP (Finsterer et al. 2012). Here, L1CAM is linked to hereditary spastic paraplegia.