The purpose of the HSP Sequencing Initiative is to better understand the role of genetics in hereditary spastic paraplegia (HSP) and related disorders. The HSPs are a group of more than 80 inherited neurological diseases that share the common feature of progressive spasticity. Collectively, the HSPs present the most common cause of inherited spasticity and associated disability, with a combined prevalence of 2-5 cases per 100,000 individuals worldwide. In childhood-onset forms, initial symptoms are often non-specific and many children may not receive a diagnosis until progressive features are recognized, often leading to a significant diagnostic delay. Genetic testing in children with spastic paraplegia is not yet standard practice. In this study, the investigators hope to identify genetic factors related to HSP. By identifying different genetic factors, the investigators hope that over time we can develop better treatments for sub-categories of HSP based on cause.