Nefropatía C1q: diagnóstico inusual de síndrome nefrótico en la infancia. Reporte de caso / C1q nephropathy: unusual diagnosis of nephrotic syndrome in childhood. Case report

RESUMEN La nefropatía C1q es una glomerulopatía poco comprendida y subdiagnosticada. Se define por un patrón de inmunfluorescencia dominante o codominante de positividad para C1q, con depósitos electrodensos en mesangio, en ausencia de serología y clínica de lupus eritematoso sistémico. Clínicamente se manifiesta con proteinuria severa o de rango nefrótico, en ocasiones hematuria e hipertensión arterial. Histológicamente presenta morfología variada. Usualmente se manifiesta como síndrome nefrótico corticodependiente o corticoresistente con mala respuesta al tratamiento inmunosupresor y evolución a la cronicidad. Se presenta el caso clínico de un niño diagnosticado con nefropatía C1q, a quien se indicó biopsia renal por cuadro de síndrome nefrótico corticorresistente, con serología negativa y ausencia de datos clínicos para lupus eritematoso sistémico. La intervención oportuna y el manejo temprano permiten enlentecer su evolución a la cronicidad

ABSTRACT C1q nephropathy is a poorly understood and underdiagnosed glomerulopathy. It is defined by a dominant or codominant immunfluorescence pattern of C1q positivity, with electrodense deposits in the mesangium, in the absence of serology and symptoms of systemic lupus erythematosus. Clinically, it manifests with severe proteinuria or nephrotic range, occasionally hematuria and arterial hypertension. Histologically it presents varied morphology. It usually manifests as a corticodependent or cortico-resistant nephrotic syndrome with poor response to immunosuppressive treatment and evolution to chronicity. We present the clinical case of a child diagnosed with C1q nephropathy, who underwent a renal biopsy due to corticosteroid-resistant nephrotic syndrome, with negative serology and absence of clinical data for systemic lupus erythematosus. Timely intervention and early management slow down its progression to chronicity

Primer caso registrado en Cuba de nefropatía C1q / First case of C1q nephropathy in Cuba

La nefropatía C1q es una glomerulopatía no comprendida completamente y con algunas controversias conceptuales, pero con característica inmunológica distintiva (depósito dominante o co-dominante de C1q) y no evidencia clínica ni serológica de lupus eritematoso sistémico. Se presenta paciente masculino que comienza a los 10 meses de edad con un síndrome nefrótico con hematuria, hipertensión arterial e insuficiencia renal. Se realiza una primera biopsia renal y se plantea una esclerosis mesangial difusa, pero su evolución posterior con respuesta parcial a la prednisona y el mantenimiento de proteinuria en rango nefrótico con normalización de los parámetros humorales, nos lleva a realizar una segunda biopsia renal que arroja, por la inmunofluorescencia, una nefropatía C1q

C1q nephropathy is a poorly understood glomerulopathy with some conceptual controversies, but with a distinctive immunologic characteristic (dominant or co-dominant deposit of C1q) and neither clinical nor serological evidence of systemic erythematous lupus. This is the case of a male patient who began suffering nephritic syndrome with hematuria, blood hypertension and renal failure at 10 months of age. A first renal biopsy was performed to detect diffuse mesangeal sclerosis; however after partial response of the patient to prednisone therapy and to maintenance treatment of proteinuria in nephritic range, with normalization of humoral parameters, then a second renal biopsy was performed with immunofluorescence. The final result was C1q nephropathy

Two Cases of C1q Nephropathy in Siblings

C1q nephropathy is a distinct clinicopathologic entity, characterized by mesangial immunoglobulin and complement deposits, predominantly C1q, with no evidence for systemic lupus erythematosus. Clinically it may present as nephrotic syndrome and non-nephrotic proteinuria per se or associated with microscopic hematuria, gross hematuria, hypertension, or renal insufficiency. So far there is only one report about a familial case of C1q nephropathy (in two sisters). We present two cases of familial C1q nephropathy with nephrotic syndrome which was steroid resistant, but partially remitted with cyclosporine.

Clinicopathological features and treatment of C1q nephropathy in children / 中华肾脏病杂志

Objective To investigate the clinicopathological characteristics and treatment of C1q nephropathy in children.Methods Data of 23 C1q nephropathy cases in Nanjing Children's Hospital during recent eight years were retrospectively reviewed. Results The incidence of C1q nephropathy was 4.78％ in primary glomerulonephritis proven by biopsy.Among 23 patients,15 were boys and 8 were girls.The mean age at onset was (5.0±3.4) years old with a range of 0.9-12.4 years.The clinical manifestations included nephrotic syndrome(NS) in 18 cases (78.3％),nephrotic-range proteinuria in 4 cases(17.4％) and microhematuria in 1 case.Two patients with NS and one patient with nephrotic-range proteinuria also presented microhematuria.One patient with NS who received oral herbal medicine for two weeks developed acute renal insufficiency at the same time of diagnosis.Three cases had a family history of kidney disease,among them two patients(presented nephrotic range proteinuria) were siblings,their father had proteinuria as well,and routine genetic examination confirmed familial Denys-Drash syndrome in association with C1q nephropathy.One NS patient's sister had nephrotic-range proteinuria too,but renal biopsy was not performed.No patient had hypertension.None of the patients had low C3 or C4 levels,and serological markers of systemic lupus erythematosus were absent.Light microscopy showedminimalchangedisease (MCD)in13cases (56.5％), mesangialproliferative glomerulonephritis(MsPGN) in 6(26.1％) and focal segmental glomerulosclerosis(FSGS) in 4(17.4％).Immunofluorescence displayed C1q co-deposits of IgG(78.3％),IgM(78.3％),IgA (34.8％) and C3 (47.8％),and a full-house pattern was found in 6 patients (26.1％).Electron microscopy revealed 4 out of 19 had mesangial deposits,except for 4 patients whose glomerulus could not be found.Children with either NS(18 cases) or nephrotic-range proteinuria(2 cases)received prednisone,among them,15 were steroid-resistant,4 were steroid-dependent,only 1 was steroid-sensitive.Those with steroid-resistant(15 cases) or steroid-dependent(3 cases) received further immunosuppression with cyclophosphamide(CTX) or cyclosporine A (CsA).One NS case of steroid-dependent received prednisone re-induction therapy.The siblings associated with DenysDrash syndrome and one case presented microhematuria were commenced on angiotensin-converting enzyme inhibitor(ACEI).Of the 19 patients with sufficient follow-up date,15 cases (78.9％)achieved complete remission,2 cases(10.5％) achieved partial remission,and 2 cases (10.5％) were ineffective.Median follow-up was 15 months.Remission of the NS occurred in 94.4％ (17/18)while nephrotic-range proteinuria was 50.0％(2/4).Remission of MCD was 100.0％,MsPGN was 83.4％(5/6),but FSGS was only 50.0％(2/4).Conclusions C1q nephropathy is rare,and often manifests as steroid-resistant or steroid-dependent NS and nephrotic-range proteinuria.The most common histological feature is MCD,and some as MsPGN or FSGS.A combination of prednisone and immunosuppressive agent is always effective for MCD and MsPGN,but FSGS always has a poor response.

Proteinuria in a Boy with Infectious Mononucleosis, C1q Nephropathy, and Dent's Disease

C1q nephropathy is a proliferative glomerulopathy with extensive mesangial deposition of C1q. A three-year old boy presented with a nephrotic-range proteinuria during an acute phase of Epstein-Barr virus (EBV) infection, and he had a family history of Dent's disease. The renal biopsy findings were compatible with C1q nephropathy. However, EBV in situ hybridization was negative. The CLCN5 gene analysis revealed an R637X hemizygous mutation, which was the same as that detected in his maternal cousin, the proband of the family. The causal relationship between EBV infection and C1q nephropathy remains to be determined. Moreover, the effects of underlying Dent's disease in the process of C1q nephropathy has to be considered.

A Case of C1q Mediated Glomerulonephritis Manifested by Asymptomatic Hematuria / 대한신장학회잡지

C1q nephropathy is an immune complex glomerulonephritis defined by predominant mesangial C1q deposition and has no evidence of systemic lupus erythematosus. Patients are usually between the ages of 15 and 30 when diagnosed and have a nephrotic range proteinuria. C1q nephropathy in adult has not been reported yet in Korea. Also it may be accompanied by hematuria, but it is uncommonly manifested hematuria without proteinuria. We experienced a case of C1q mediated glomerulonephritis that manifested by asymptomatic hematuria in adult. A 47-years-old man visited our hospital complaining general weakness and fatigue. Microscopic hematuria was detected on routine examination of urinary sediment so that renal biopsy was carried out. Renal biopsy showed C1q mediated glomerulonephritis. We report a case of C1q mediated glomerulonephritis manifested by asymptomatic hematuria without proteinuria. C1q nephropathy should be added to the differential diagnosis of glomerulonephritis in patients with asymptomatic hematuria.

A Case of C1q Nephropathy in Steroid-Dependent Nephrotic Syndrome

C1q nephropathy is an immune complex glomerulonephritis defined by the presence of mesangial C1q deposits in immunofluorescence microscopy and electron dense deposits on electron microscopy. It was described as a distinct disease entity in 1985 by Jennette and Hipp. Thirty four cases were reported in the literature but there has been no pediatric case reported in Korea yet. It commonly presents with steroid-resistent nephrotic syndrome in older children and young adults, and occasionally nephritic-nephrotic syndrome or rapidly progressive glomerulonephritis. We report a case of C1q nephropathy in a 23-month-old girl with steroid-dependent nephrotic syndrome.