An extremely rare and complex form of hereditary spastic paraplegia (see this term), reported in only 4 patients from 2 families to date, characterized by spastic paraplegia (presenting between the ages of 1 to 4 years with abnormal gait) associated with microcephaly, amyotrophy, cerebellar signs (e.g. dysarthria) aggressiveness, delayed puberty and mild to moderate intellectual disability. SPG64 is due to mutations in the ENTPD1 gene (10q24.1), encoding ectonucleoside triphosphate diphosphohydrolase 1. The disease is Monarch Disease Ontology identifier MONDO_0014303 (hereditary spastic paraplegia 64). Also known as: ENTPD1 autosomal recessive complex spastic paraplegia, SPG64, autosomal recessive complex spastic paraplegia caused by mutation in ENTPD1, autosomal recessive spastic paraplegia 64, autosomal recessive spastic paraplegia type 64, hereditary spastic paraplegia type 64.