UCD is thought to arise via a neoplastic process most likely involving follicular dendritic cells.[7] Multiple processes have been hypothesized to play a role in iMCD including neoplastic cells, autoinflammation/autoimmunity, and infection.[7] Though the etiology of iMCD is unknown, interleukin-6 (IL-6) is the pathological driver in a large portion of cases. Here, IL6 is linked to urea cycle disorder.