Hall mark of the IgA nephropathy is -

IgA nephropathy, characterized by mesangial deposits of IgA-containing immune complexes, is the most common cause of the nephritic syndrome worldwide; it is also a common cause of recurrent hematuria; it commonly affects children and young adults and has a variable course. Ref: Robbins basic book of pathology 9th edition page 531 The clinical picture is usually characterized by recurrent bouts of haematuria that are often precipitated by mucosal infections. Mild proteinuria is usually present and occasionally nephrotic syndrome may develop. Ref: HARSH MOHAN TEXTBOOK OF PATHOLOGY 6th ed. pg no: 674