A case of antiglomerular basement membrane glomerulonephritis complicated by membranous nephropathy.

The sequential or simultaneous presentation of anti-glomerular basement membrane (anti-GBM) glomerulonephritis with membranous nephropathy (MN) has been infrequently reported. Although the mechanism underlying MN superimposed on anti-GBM glomerulonephritis is unknown, the two entities are believed to be interrelated. We report the case of a 75-year-old woman diagnosed with rapidly progressive glomerulonephritis. Renal biopsy revealed crescentic glomerulonephritis with linear and granular staining of immunofluorescent IgG1 and IgG4 granular staining on the capillary loops. Electron microscopy revealed extensive subepithelial deposits. These findings suggested simultaneous development of anti-GBM glomerulonephritis and MN in this case. Serum phospholipase A2 receptor (PLA2R) antibody was negative. The patient was treated with prednisolone and plasma exchange, resulting in resolution of renal insufficiency and a decrease in urinary protein. The rapid decrease in urinary protein and absence of PLA2R antibody suggest that the mechanism of MN associated with anti-GBM glomerulonephritis differs from that of primary MN.

A case of podocytic infolding glomerulopathy with focal segmental glomerulosclerosis.

Podocytic infolding glomerulopathy (PIG) has been proposed as a new disease entity. A 14-year-old girl underwent renal biopsy at our institution because of a chance finding of proteinuria. Light microscopic findings revealed a minor glomerular abnormality, but under a higher magnification, after periodic acid methenamine silver staining, a bubbling appearance in the glomerular basement membrane (GBM) was observed. An electron microscopic examination revealed microspheres in the GBM, which were sparse but global. The patient was diagnosed as having PIG. After 3 years, her urinary protein had increased and a second biopsy was performed, showing focal segmental glomerulosclerosis in addition to a lesser degree of podocytic infolding than at the first biopsy. This is the first report of a case complicated by a different type of glomerulonephritis after being diagnosed as PIG. A few cases of PIG are complicated by focal segmental glomerulosclerosis, suggesting several mechanisms for the disorder.

A novel mutation in the uromodulin gene in a Japanese family with a mild phenotype of familial juvenile hyperuricemic nephropathy.

Familial juvenile hyperuricemic nephropathy (FJHN) is an autosomal-dominant disorder that is characterized by hyperuricemia and chronic renal failure and results in end-stage renal failure. FJHN is caused by mutations in the UMOD gene, which encodes uromodulin. Uromodulin contains three epidermal growth factor (EGF)-like domains, a domain of eight cysteine residues (D8C), and a zona pellucid-like domain. Over 90 % of UMOD mutations are missense mutations, and over 80 % exist in exon 4, which encodes both D8C and the EGF-like domains. A 56-year-old woman was diagnosed with hyperuricemia with a serum uric acid level of 7.5 mg/dL, and stage III chronic kidney disease (CKD) with a serum creatinine level of 1.12 mg/dL and an estimated glomerular filtration rate of 39.9 mL/(min 1.73 m2). The patient had a family history of hyperuricemia and stage IV CKD; both the patient and her affected family members had a novel mutation in the UMOD gene: c.C518G (p.P173R), located between the EGF-like domains and D8C. This mutation, along with previously reported nearby mutations, causes a clinically mild phenotype of FJHN. It is important that physicians consider the diagnosis of FJHN in patients with a family history of hyperuricemia associated with renal dysfunction, even if the patient has only mild renal impairment.