Any autosomal recessive complex spastic paraplegia in which the cause of the disease is a mutation in the ALDH18A1 gene. The disease is Monarch Disease Ontology entry MONDO_0014702 (autosomal recessive complex spastic paraplegia type 9B). Also known as: ALDH18A1 autosomal recessive complex spastic paraplegia, AR-SPG9B, SPG9B, autosomal recessive complex spastic paraplegia caused by mutation in ALDH18A1, autosomal recessive spastic paraplegia 9B, hereditary spastic paraplegia type 9B.