Chronic Renal Failure and Abnormal Tubular Cells in 2 Siblings

Clinical history. A 41-year-old white man presented ith diaphoresis, weakness, and nausea. A workup for anina was performed, and he was noted to have underlying enal insufficiency of unknown cause, with a serum creatiine level of 2.0 mg/dL (177 mol/L). The patient had no istory of hypertension or diabetes mellitus. He had a history f rare cigarette use, with no significant alcohol consumpion. His family history indicated his brother had chronic enal failure of unknown cause. Findings from the remaining review of systems and physial examination were negative. Pertinent laboratory values ncluded a blood urea nitrogen level of 23 mg/dL (8.2 mol/L), creatinine clearance of 59 mL/min (0.98 mL/s), nd 24-hour urinary protein excretion of 285 mg. Serum rotein electrophoresis, renal ultrasound, and renal scans ere normal. A percutaneous renal biopsy was performed in June 2000. Renal biopsy. The renal biopsy specimen contained corical tissue with 37 glomeruli, 24 of which were hyalinized. n light microscopy, there was only a very focal segmental ncrease in mesangial matrix. There was segmental glomeruar basement membrane corrugation, but no spikes, holes, or