Autosomal recessive spastic paraplegia-84 (SPG84) is characterized by onset of slowly progressive walking difficulties due to lower limb weakness, stiffness, and spasticity in the first 2 decades of life. Additional features may include nystagmus, urinary urgency, joint contractures, and possible learning disabilities. The disease is spastic paraplegia 84, autosomal recessive (Experimental Factor Ontology entry EFO_0020858).