Autosomal dominant spastic paraplegia type 4 (SPG4) is a form of hereditary spastic paraplegia with high intrafamilial clinical variability, characterized in most cases as a pure phenotype with an adult onset (mainly the 3rd to 5th decade of life, but that can present at any age) of progressive gait impairment due to bilateral lower-limb spasticity and weakness as well as very mild proximal weakness and urinary urgency. In some cases, a complex phenotype is also reported with additional manifestations including cognitive impairment, cerebellar ataxia, epilepsy and neuropathy. A faster disease progression is noted in patients with a later age of onset. The disease is hereditary spastic paraplegia 4 (MONDO_0008438, a Monarch Disease Ontology term). Also known as: SPAST hereditary spastic paraplegia, SPG4, autosomal dominant spastic paraplegia 4, autosomal dominant spastic paraplegia type 4, hereditary spastic paraplegia caused by mutation in SPAST, hereditary spastic paraplegia type 4.