# A Decade of C3 Glomerulopathy—A Nationwide Cohort Study

## TL;DR

This study examines the incidence and characteristics of C3 glomerulopathy in the Netherlands over a decade, revealing subtype differences and consistent diagnosis patterns.

## Contribution

The study provides the first nationwide analysis of C3 glomerulopathy subtypes and their clinical and histopathological features in the Netherlands.

## Key findings

- C3GN was most common, followed by unspecified C3G and DDD.
- Age at diagnosis varied significantly between subtypes, with DDD affecting younger patients.
- Geographical factors did not influence disease development or diagnosis consistency.

## Abstract

C3 glomerulopathy (C3G) is a rare but devastating disease affecting children and adults. It frequently leads to end-stage kidney failure, and currently no specific treatment exists. C3G is used as a collective term for dense deposit disease (DDD) and C3 glomerulonephritis (C3GN) and is thought to sometimes occur in postinfectious settings (C3-PIGN). Currently, little is known about the incidence and distribution of subtypes in the population. We analyzed a large cohort of patients with C3G in the Netherlands regarding incidence and disease subtype distribution in relation to geographical factors and histopathological findings.

A search in the Dutch Nationwide Pathology Databank (Palga) was performed to identify patients diagnosed with C3G from January 2014 until December 2023, subsequently ascertained by 2 independent observers. We assessed the correlation of disease subtypes with glomerular patterns, and the geographical distribution was charted.

The selection resulted in a cohort of 280 patients consisting of C3GN (n = 101), DDD (n = 39), unspecified C3G (n = 106), C3-PIGN (n = 29), and others (n = 5). The median age at biopsy diagnosis was 19 (range: 4–75) years for DDD and 54 (range: 2–86) years for C3GN, showing age distribution depends on C3G subtype (P < 0.001). DDD and C3G were associated with membranoproliferative pattern and C3-PIGN with endocapillary or exudative pattern.

Our results show consistent assessment of kidney biopsies across the country and absence of geographical factors influencing disease development.