CYP7B1 and hereditary spastic paraplegia: The most common types of AR HSP are SPG5A, caused by pathogenic variants in CYP7B1, which accounts for 7.3% of all AR HSP; SPG7, caused by pathogenic variants in SPG7 gene of chromosome 16q24.3, accounting for approximately 5% of all AR HSP; and SPG11, caused by pathogenic variants in SPG11/KIAA1840 gene on chromosome 15p (3–5% of all AR HSP).