A rare, complex form of hereditary spastic paraplegia characterized by the onset in early childhood of progressive spastic paraplegia associated with cerebellar signs, short stature, delayed psychomotor development, intellectual disability and, less commonly, foot contractures, dysarthria, dysphagia, strabismus and optic hypoplasia. SPG54 is caused by mutations in the DDHD2 gene (8p11.23) encoding phospholipase DDHD2. The disease is hereditary spastic paraplegia 54 (Monarch Disease Ontology term MONDO_0014018). Also known as: DDHD2 autosomal recessive complex spastic paraplegia, SPG54, autosomal recessive complex spastic paraplegia caused by mutation in DDHD2, autosomal recessive spastic paraplegia 54, autosomal recessive spastic paraplegia type 54, hereditary spastic paraplegia type 54.