IL6 and hereditary spastic paraplegia: By comparing the levels of IL-6, TNF-α, MDA, superoxide dismutase (SOD), and total anti-oxidant capability (T-AOC) in the acute phase of HSP children with different clinical manifestations, and the correlation between IL-6, TNF-α, MDA and renal pathological grade, as well as comparison of the changes of IL-6, TNF-α, MDA, SOD and T-AOC levels before and after HP treatment in children with severe HSP with GI involvement and the clinical outcomes.