C3 and hereditary spastic paraplegia: Based on the data from 13 studies encompassing 2398 HSP patients, a meta-analysis by Chan et al. [8] indicated that some risk factors were predictive of HSPN, including relapse (OR = 4.7), persistent purpura (OR = 4.0), severe bowel angina (OR = 3.4), decreased C3 (OR = 3.1), age > 10 years (OR = 3.1), platelets > 500 × 109/L (OR = 3.0), WBC > 15 × 109/L (OR = 2.4), elevated ASO (OR = 2.2), abdominal pain (OR = 1.9), gastrointestinal bleeding (OR = 1.9), male gender (OR = 1.4) and older age (OR = 0.9).