Kanzaki Motoko, Kurahashi Motoyasu, Watanabe Kentaro, Nishikawa Mana, Fukuoka Kosuke, Shimada Noriaki, Mizuno Masashi, Asano Kenichiro
Department of Nephrology, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki, 710-8602, Japan.
Department of Renal Replacement Therapy, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Syowa-Ku, Nagoya, 466-8550, Japan.
CEN Case Rep. 2025 Apr;14(2):188-193. doi: 10.1007/s13730-024-00928-5. Epub 2024 Sep 12.
C3 glomerulopathy is a rare disease that results in nephritis due to complement dysregulation and is characterized by C3 deposition in the glomerulus. Dysregulation of the alternative pathway underlies the pathogenesis, but activation of the terminal pathway is also common. The disease is often caused by acquired rather than genetic factors, i.e., autoantibodies against C3 or C5 converting enzyme (convertase) and other complement-related proteins. We report a case of C3 glomerulopathy diagnosed by renal biopsy that responded well to corticosteroids and went into complete remission within two months. Analysis of complements and complement-related proteins revealed a low level of C3 and a high level of soluble terminal pathway protein complex (sC5b-9). Under genetic analysis about complement-related genes, no pathogenic variant was observed. Based on these findings, we diagnosed this patient with C3 glomerulopathy with autoantibodies. Corticosteroids had a marked effect, which also supports this speculation. Analyses of complements and complement-related proteins, and genetic variants may be useful in understanding the pathogenesis of C3 glomerulopathy and in selecting treatment options.
C3肾小球病是一种罕见疾病，由于补体调节异常导致肾炎，其特征是C3在肾小球沉积。替代途径的调节异常是发病机制的基础，但终末途径的激活也很常见。该疾病通常由获得性因素而非遗传因素引起，即针对C3或C5转化酶及其他补体相关蛋白的自身抗体。我们报告一例经肾活检诊断为C3肾小球病的病例，该病例对皮质类固醇反应良好，并在两个月内完全缓解。补体及补体相关蛋白分析显示C3水平低，可溶性终末途径蛋白复合物（sC5b-9）水平高。在对补体相关基因进行基因分析时，未观察到致病变异。基于这些发现，我们将该患者诊断为伴有自身抗体的C3肾小球病。皮质类固醇有显著效果，这也支持了这一推测。补体及补体相关蛋白分析和基因变异可能有助于理解C3肾小球病的发病机制并选择治疗方案。
