Dr. Arshad Ali (AA), from Emory University School of Medicine in Atlanta, Georgia, discusses his abstract for the National Kidney Foundation’s 2015 Spring Clinical Meetings (SCM15), Proliferative C4 Dense Deposition Disease Concurrent with Acute Thrombotic Microangiopathy in an Adult Patient with Acute Renal Failure, with Dr. Kenar Jhaveri, AJKD Blog Editor.

AJKDblog: Why don’t you tell us a little about your research and abstract being presented at the NKF 2015 Spring Meetings?

AA:  We present a novel case of C4 dense deposit disease concurrent with acute thrombotic microangiopathy (TMA) in a 54 year old Caucasian male who presented with acute kidney injury. Both DDD and C3 GN are characterized by alternative complement pathway abnormalities. Recently, a form of dense deposit disease characterized by C4d staining dense deposits has been described. This form of dense deposit disease differs from the typical DDD in that the deposits stain for C4d but are negative for C3. A single report of C4-DDD showed over-activation of the lectin pathway, but no abnormalities of the alternative pathway were detected. We report the first case of C4 Dense deposit disease concurrent with TMA. One previous case of C4 dense deposit disease had been reported in an adolescent female and our current case demonstrates it can occur in adults. The two cases suggest that the rare C4 dense deposit disease needs to be distinguished from C3 glomerulopathies.

AJKDblog: Do you think there is a genetic disposition for C4 glomerulonephritis?

AA:  Although there is significant evidence that genetics plays a role leading to mutations in the alternative complement pathway regulation factors which are involved in C3 GN/ DDD, the role of genetics in C4 dense deposit disease is not clear.  One prior case involving the lectin pathway was reported in an adolescent female, and given the patient’s young age there may have been a genetic disposition. Additional research on the specific pathways for C4 glomerulopathies would help answer this question.

AJKDblog: How did you treat this patient?

AA:  He was empirically started on prednisone 60 mg daily, and both glomerulopathy and acute interstitial nephritis were high on the differential. Prior to the kidney biopsy, he developed hypoxic respiratory failure with pulmonary edema, and he was started on emergent hemodialysis. In the interim his platelets continued to drop to 37 x 10³/µL, with LDH at 426 IU/L, reticulocyte count elevated at 2.45%, haptoglobin level <7 mg/dL, and a blood smear showing 5-6 schistocytes/HPF. He was noted to have mental status changes and was continued on prednisone and he underwent 6 sessions of plasmapheresis with no improvement in his platelet level or renal function.  At the time of this writing he continues to be dialysis dependent (14 months post biopsy).

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