CD4 and hereditary spastic paraplegia: Correlation analysis showed that the number of red blood cells (RBCs) in urine was positively correlated with IgA level in children with HSP having hematuresis (r = 0.288, P = 0.023) and negatively correlated with the proportion of CD4+ T cells (r = −0.253, P = 0.046) and complement C4 level (r = −0.269, P = 0.034).