Studies analyzing patient biopsies indicate a possible mechanistic role of streptococcal surface proteins or streptococcal antigens in HSP and IgA nephropathy, as deposits of IgA-binding streptococcal surface proteins were detected in 54% of kidneys and 80% of skin biopsies32 and streptococcal antigen overexpression was reported in 30% of patients’ kidney mesangium.33 Further studies are needed to understand the exact pathologic mechanisms linking streptococcal infections to the development of HSP. Here, CD79A is linked to hereditary spastic paraplegia.