Hereditary spastic paraplegia (HSP) is an inherited neurodegenerative disease that causes progressive weakness of the lower limbs with a heterogeneous phenotype spectrum according to the gene involved, and spastic paraplegia 4 (SPG4) is the most common form of HSP.1-3 SPG4 is caused by a pathogenic variant in the SPAST gene at locus p22.3 of chromosome 2 and can be sporadic or inherited in an autosomal dominant manner. The gene discussed is SPAST; the disease is neurodegenerative disease.