Hereditary spastic paraplegia is a group of genetic degenerative diseases of the nervous system with symmetrical bilateral lower extremity progressive muscle weakness and increased muscle tone as the main manifestation. The estimated prevalence rate abroad is 9.6/100,000, and no epidemiological findings are available for this disease in China. The disease can develop from infancy to adulthood, and the duration of the disease can be short or long. According to the clinical manifestations, the disease can be divided into simple and complex types. The simple form refers to progressive spastic muscle weakness of both lower extremities, which may be accompanied by bladder dysfunction and profound sensory abnormalities, while the complex form is associated with other neurological symptoms (such as cataract, retinitis pigmentosa, mental retardation, ataxia, and agenesis of the corpus callosum) in addition to the clinical manifestations of the simple form. There are 3 modes of inheritance of HSP, as autosomal dominant, autosomal recessive and X-linked recessive, and some families may have only one patient (which may be incompletely episodic, or recessive). HSP has the following 3 clinical characteristics: 1. apparent genetic heterogeneity: i.e. different genes can cause the same disease; 2. allelic heterogeneity: i.e. different mutations of the same gene can cause the same or different diseases; 3. clinical heterogeneity: i.e. different individuals with the same mutation can have different symptoms even in the same family. In the clinical setting, simplex HSP accounts for the majority of cases. The qualitative diagnosis of simplex HSP is often difficult because of its heterogeneity and intricate phenotype, and because this group of disorders also has intertwined clinical features with hereditary ataxia and spinal cord disorders. Forty-three loci have been reported to be associated with HSP, of which 18 genes have been cloned.