探讨3例儿童C3肾小球肾炎(C3GN)的临床和病理特点，并结合相关文献进行分析，以提高临床医师对该病的认识和诊治水平。

选择2015年11月至2017年3月，在中山大学附属第一医院小儿肾病中心住院，并确诊为C3GN的3例患儿为研究对象。回顾性分析3例C3GN患儿的临床表现、肾脏病理改变、基因检测结果、治疗及预后情况，并结合国内外C3肾小球病(C3G)相关文献进行文献复习，总结C3GN临床特点。

对3例C3GN患儿的相关研究结果如下。①临床表现：2例以血尿和蛋白尿为首发表现，1例以血尿为首发表现；2例起病前1周有"上呼吸道感染"病史伴抗链球菌溶血素(AS)O升高，血C3水平下降；1例起病时伴急性肾损伤。②肾活检病理学检查结果：免疫荧光检查显示3例在系膜区均可见单纯C3(＋＋～＋＋＋)沉积；光镜检查显示1例肾小球膜增生，1例肾小球毛细血管内增生伴新月体形成，1例轻度系膜增生；电镜结果显示，3例系膜区均有电子致密物沉积。③其中2例进行基因检测的结果：1例检测到C3基因杂合突变，另1例未发现基因突变。④治疗及预后：1例C3GN患儿仅采用对症治疗。另外2例给予激素治疗，并联合抗凝血药或血管紧张素转换酶抑制剂(ACEI)治疗。对3例患儿治疗结束后随访8～13个月的结果显示，1例预后较好，尿常规、肾功能检查和血C3正常；另外2例仍然存在持续镜下血尿和低C3血症，其中1例仍有蛋白尿。⑤文献检索出3篇C3G相关研究，共计纳入28例C3G患儿，结合本研究3例C3GN患儿临床资料进行研究的结果显示：C3G好发于学龄期儿童，男、女个体均可发病，前期常合并上呼吸道感染病史，临床表现主要为血尿、蛋白尿及低C3血症，部分患儿可伴水肿、高血压、ASO升高及肾功能损害。

C3GN临床表现与急性链球菌感染后肾小球肾炎(APSGN)相似，二者的鉴别诊断依据为肾活检病理学检查结果。目前对于C3GN患儿的诊断与治疗，亟需更方便、有效的检查方法和药物，以利于该病患儿的早期诊断及改善其预后。

To study the clinical and pathological features of three children with C3 glomerulonephritis (C3GN) and summarize the relevant literatures to improve the levels of cognition and diagnosis of C3GN in children for clinician.

From November 2015 to March 2017, three children with C3GN who were hospitalized in Children′s Nephrology Center in First Affiliated Hospital of Sun Yat-sen University, were chosen as study subjects. Clinical manifestations, renal pathology, gene test results, treatment and prognosis of 3 cases of C3GN children were retrospectively analyzed, and summarized clinical characteristics of C3GN with the related literatures of C3 glomemlopathy (C3G) at home and abroad.

Study results of 3 cases of C3GN were as follows. ①Clinical manifestations: hematuria and proteinuria were the first performance in 2 cases, and hematuria was the first performance in another case. Two cases had upper respiratory infections duration 1 week before onset of the disease, with high level of antistreptolysin (AS)O and level of serum complement C3 decreased.One case with acute kidney injury at onset. ②Renal biopsy pathological examination results: immunofluorescence only observed high intensity of complement C3 deposition (+ + to + + + ) in the mesangial area in 3 cases. Light microscopy showed that mesangial proliferative in 1 case, glomerular capillary hyperplasia with crescent formation in 1 case, and mild mesangial hyperplasia in another case. All 3 cases presented electron dense depositional under electron microscope. ③Gene test results of two cases who took genetic test: one of them was found C3 gene heterozygous mutation, and no mutation was found for the other one. ④Treatment and prognosis: 1 C3GN child only took symptomatic treatment; the other two cases were treated with hormone therapy, and combined with anticoagulants or angiotensin converting enzyme inhibitor (ACEI). They were followed up for 8 months to 13 months after treatment, one case had good prognosis with normal urine routines, renal functions and level of serum complement C3. While the other two cases were presented with persistent microscopic hematuria and low levels of serum complement C3, moreover one of them still had proteinuria. ⑤There were 3 related literatures of C3G were searched from database with a total of 28 C3G children, and with 3 cases of C3GN in this study, it can be summarized that C3G often occured in school age children, both male and female can be attacked and often with upper respiratory tract infection before onset. The main clinical manifestations were hematuria, proteinuria and low level of serum complement C3, some children may had edema, hypertension, ASO level increased and renal injury.

The clinical manifestations of C3GN are similar to acute poststreptococcal glomerulonephritis (APSGN), differential diagnosis of them mainly depends on renal biopsy for pathological examination results. It′s urgent to find out more convenient and effective examinations and therapy to help early diagnosis and improve prognosis of C3GN children.