Characteristics of membranoproliferative glomerulonephritis based on a new classification at a single center

Characteristics and outcomes of glomerulonephritis with membranoproliferative pattern in children

BACKGROUND

Membranoproliferative glomerulonephritis (MPGN) is a rare histopathologic pattern of glomerular injury with limited studies in pediatric patients. Characteristics and outcomes of children with MPGN have also remained to be further explored.

METHODS

We retrospectively reviewed the clinicopathological features, genetic findings, treatments and outcomes in 17 pediatric patients pathologically diagnosed with MPGN from 2007 to 2020 in the Children's National Medical Center in China.

RESULTS

Median age at disease onset was 9.9 years (IQR, 5.6-11.9 years). Most of the patients (12/17) had nephrotic range of proteinuria, and nephritic-nephrotic syndrome was the most common clinical presentation (35.2%). Secondary causes were identified in eight patients including hepatitis B virus (HBV) infection (n=4), methylmalonic acidemia (MMA, n=2), rheumatoid arthritis (RA, n=1) and Aymé-Gripp Syndrome (n=1). The nine patients with primary MPGN were further identified as immune-complex mediated MPGN (n=8), and unclassifiable MPGN (U-MGPN, n=1). Genetic analyses identified pathogenic variants of MMACHC gene in two cases of MMA and established the diagnosis for Aymé-Gripp syndrome in one case with a de novo variant of MAF gene. Comparing study between the complete or partial remission group (n=8) and non-response group (n=9) showed a significant difference in the timing of renal biopsy (P<0.05). Normal renal function was preserved in ten patients at the last follow-up. Two patients developed into end-stage renal disease (ESRD).

CONCLUSIONS

Children with MPGN pattern present heterogenous clinical features. Genetic detection helps to explore underlying causes of MPGN. Early identification of the primary or secondary causes of MPGN in children is vital.

Demographic, clinical characteristics and treatment outcomes of immune-complex membranoproliferative glomerulonephritis and C3 glomerulonephritis in Japan: A retrospective analysis of data from the Japan Renal Biopsy Registry

The reclassification of membranoproliferative glomerulonephritis (MPGN) into immune-complex MPGN (IC-MPGN) and C3 glomerulopathy (C3G) based on immunofluorescence findings in kidney biopsies has provided insights into these two distinct diseases. C3G is further classified into dense deposit disease and C3 glomerulonephritis (C3GN) based on electron micrographic findings. Although these diseases have poor outcomes, limited Japanese literature confined to small, single-center cohorts exist on these diseases. We retrospectively analyzed 81 patients with MPGN type I and III from 15 hospitals in the Japan Renal Biopsy Registry to compare demographic, clinical characteristics and treatment outcomes of patients with IC-MPGN to those with C3GN. Of the 81 patients reviewed by immunofluorescence findings in kidney biopsies, 67 patients had IC-MPGN and 14 patients had C3GN. Age at diagnosis and systolic and diastolic pressure were higher and proteinuria and impaired renal function were significantly more prevalent in patients with IC-MPGN than those with C3GN. About 80% of the patients in both groups were treated with immunosuppressive therapy. At last follow-up (median 4.8 years), complete remission rate of proteinuria was significantly higher in patients with C3GN (64.3%) than in those with IC-MPGN (29.9%; P = 0.015). The renal survival rate was lower in patients with IC-MPGN when compared to C3GN (73.1% vs. 100%; log-rank, P = 0.031). Systolic blood pressure and renal function at baseline were independent predictors of progression to end-stage kidney disease. The overall prognosis of patients with C3GN is more favorable than for patients with IC-MPGN.