SPAST and hereditary spastic paraplegia: Mutations in SPAST, a member of the AAA protein family, are the most frequent cause of both sporadic and familial HSP (MIM#182601), but childhood-onset, such as that of our patient, is rare.32 Schieving et al.33 concluded recently that all pediatric SPAST-related phenotypes have been caused by de novo variants on the AAA-cassette of SPAST.