The development of clinical treatment protocols usually relies on evidence-based guidelines
that focus on randomized, controlled trials. For rare renal diseases, such stringent
requirements can represent a significant challenge. Dense deposit disease (DDD; also
known as membranoproliferative glomerulonephritis type II) is a prototypical rare disease. It
affects only two to three people per million and leads to renal failure within 10 yr in 50% of
affected children. On the basis of pathophysiology, this article presents a diagnostic and …