MYH9-related disorders display heterogeneous kidney involvement and outcome

Background

MYH9-related diseases (MYH9-RD) are autosomal dominant disorders caused by mutations of the MYH9 gene encoding the non-muscle myosin heavy chain IIA. They are characterized by congenital thrombocytopenia, giant platelets and leucocyte inclusions. Hearing impairment, pre-senile cataract and nephropathy can also occur. We aimed to evaluate renal involvement and outcome in MYH9-RD patients followed-up by nephrologists.

Methods

We conducted a retrospective multicentre observational study of 13 patients among 9 families with MYH9 mutation diagnosed by genetic testing and immunofluorescence assay referred to nephrologists.

Results

At initial referral, median age was 30 (range 14–76) years. Median estimated glomerular filtration rate was 66 mL/min/1.73 m² (0–141) and two patients had already end-stage renal disease (ESRD). Renal presentation associated proteinuria (n = 12), haematuria (n = 6) and hypertension (n = 6). Three patients developed a rapid onset ESRD whereas five others had a relatively stable kidney function over a 3-year median follow-up (1–34). Extra-renal features varied widely, with hearing impairment in six patients, cataract in two and mild liver dysfunction in seven. Thrombocytopenia existed at referral in 11 patients. Time to diagnosis varied from 0 to 29 years (median 3 years). Initial diagnoses such as idiopathic thrombocytopenic purpura (n = 4) and focal segmental glomerulosclerosis (n = 1) led to corticosteroid administration (n = 4), intravenous immunoglobulins (n = 3), cyclophosphamide (n = 1) and splenectomy (n = 1).

Conclusions

Renal involvement and outcome in MYH9-RD are heterogeneous. The diagnosis is often delayed and misdiagnoses can lead to unnecessary treatments. MYH9-RD should be considered in any patient with glomerular involvement associated with a low or slightly decreased platelet count and/or hearing loss and liver dysfunction.

Clinical and mutational spectrum of hypoparathyroidism, deafness and renal dysplasia syndrome

Background

Hypoparathyroidism, deafness and renal dysplasia (HDR) syndrome is a rare autosomal dominant disorder, secondary to mutations in the GATA-3 gene. Due to its wide range of penetrance and expressivity, the disease may not always be recognized. We herein describe clinical and genetic features of patients with HDR syndrome, highlighting diagnostic clues.

Methods

Medical records of eight patients from five unrelated families exhibiting GATA-3 mutations were reviewed retrospectively, in conjunction with all previously reported cases.

Results

HDR syndrome was diagnosed in eight patients between the ages of 18 and 60 years. Sensorineural deafness was consistently diagnosed, ranging from clinical hearing loss since infancy in seven patients to deafness detected only by audiometry in adulthood in one single patient. Hypoparathyroidism was present in six patients (with hypocalcaemia and inaugural seizures in two out of six). Renal abnormalities observed in six patients were diverse and of dysplastic nature. Three patients displayed nephrotic-range proteinuria and reached end-stage renal disease (ESRD) between the ages of 19 and 61 years, whilst lesions of focal and segmental glomerulosclerosis were histologically demonstrated in one of them. Interestingly, phenotype severity differed significantly between a mother and son within one family. Five new mutations of GATA-3 were identified, including three missense mutations affecting zinc finger motifs [NM_001002295.1: c.856A>G (p.N286D) and c.1017C>G (p.C339W)] or the conserved linker region [c.896G>A (p.R299G)], and two splicing mutations (c.924+4_924+19del and c.1051-2A>G). Review of 115 previously reported cases of GATA-3 mutations showed hypoparathyroidism and deafness in 95% of patients, and renal abnormalities in only 60%. Overall, 10% of patients had reached ESRD.

Conclusions

We herein expand the clinical and mutational spectrum of HDR syndrome, illustrating considerable inter- and intrafamilial phenotypic variability. Diagnosis of HDR should be considered in any patient with hypoparathyroidism and deafness, whether associated with renal abnormalities or not. HDR diagnosis is established through identification of a mutation in the GATA-3 gene.

Randomized Clinical Trial of Sevelamer Carbonate on Serum Klotho and Fibroblast Growth Factor 23 in CKD

BACKGROUND AND OBJECTIVES

Epidemiologic studies suggest that higher serum phosphaturic hormone fibroblast growth factor 23 levels are associated with increase morbidity and mortality. The aim of the FGF23 Reduction Efficacy of a New Phosphate Binder in CKD Trial was to evaluate the effect of sevelamer carbonate on serum C-terminal fibroblast growth factor 23 levels in normophosphatemic patients with CKD stage 3b/4.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients with CKD, eGFR between 45 and 15 ml/min per 1.73 m2, fasting serum phosphate concentration >3.1 mg/dl, and serum C-terminal fibroblast growth factor 23 >80 relative units/ml were included in our double-blind, placebo-controlled, randomized multicenter study. All patients received 100,000 IU cholecalciferol at time of randomization. Participants received either placebo or sevelamer carbonate 4.8 g daily during a 12-week period. Biologic parameters, including serum C-terminal fibroblast growth factor 23, intact fibroblast growth factor 23, and α-klotho, were evaluated at baseline and 12 weeks after inclusion.

RESULTS

Of 96 screened patients, 78 (mean±SD age: 63±13 years old; 70% men; mean eGFR: 27±9 ml/min per 1.73 m2) met the inclusion criteria. At baseline, mean eGFR was 27±9 ml/min per 1.73 m2, mean serum phosphate level was 3.8±0.5 mg/dl, and median (interquartile range) serum C-terminal fibroblast growth factor 23 level was 157 (120-241) relative units/ml. After 12 weeks of treatment, urinary phosphate-to-creatinine ratio fell significantly in the sevelamer group. The sevelamer and placebo groups did not differ significantly in terms of median change in serum C-terminal fibroblast growth factor 23 levels: the median (interquartile range) change was 38 (-13-114) relative units/ml in the placebo group and 37 (-1-101) relative units/ml in the sevelamer group (P=0.77). There was no significant difference in serum intact fibroblast growth factor 23, α-klotho, or phosphate levels changes between the two groups. Serum total and LDL cholesterol levels fell significantly in the sevelamer group.

CONCLUSIONS

In our double-blind, placebo-controlled, randomized study performed in normophosphatemic patients with CKD, a 12-week course of sevelamer carbonate significantly reduced phosphaturia without changing serum phosphorus but did not significantly modify serum C-terminal fibroblast growth factor 23 and intact fibroblast growth factor 23 or α-klotho levels.

Course of chronic kidney disease in French patients

Background

In 1998, a French survey showed that the referral of patients with chronic kidney disease to a nephrologist was delayed, resulting in many emergency initiations of dialysis. In 2009, the ORACLE study aimed to describe the renal course of dialysis patients from their first nephrology visit to their first dialysis session.

Methods

The ORACLE study was a multicentre retrospective study of all patients who started chronic dialysis. Data were collected at the first nephrology visit and at the first dialysis session.

Results

In total, 720 patients were included (69 centres). At the first nephrology visit, the mean Cockcroft–Gault (CG) indicator was 31.8 mL/min (22.7 in 1998) and 52.4% of patients (73% in 1998) had a CG <30. The mean time between the first nephrology visit and the first dialysis session was 48 months (35 months in 1998).

Conclusion

In 2009, most patients were referred a long time before dialysis initiation, which likely allowed them to benefit from the impact of nephrology care on early outcomes when on dialysis. However, 34.2% of the dialysis sessions were still initiated under emergency conditions.

A multicentre study of 95 biopsy-proven cases of renal disease in primary Sjögren's syndrome

Objective.

Renal involvement is a rare event during primary SS (pSS). We aimed to describe the clinico-biological and histopathological characteristics of pSS-related nephropathy and its response to treatment.

Methods.

We conducted a French nationwide, retrospective, multicentre study including pSS patients fulfilling American-European Consensus Group criteria or enlarged American-European Consensus Group criteria, and with biopsy-proven renal involvement.

Results.

A total of 95 patients were included (median age 49 years). An estimated glomerular filtration rate (eGFR) of <60 ml/min was found in 82/95 patients (86.3%). Renal biopsy demonstrated tubulointerstitial nephritis (TIN) in 93 patients (97.9%), and frequent (75%) plasma cell infiltrates. Glomerular lesions were found in 22 patients (23.2%), mainly related to cryoglobulin. The presence of anti-SSA (76.8%) and anti-SSB (53.8%) antibodies was particularly frequent among patients with TIN and was associated with a worse renal prognosis. Eighty-one patients (85.3%) were treated, with CSs in 80 (98.8%) and immunosuppressive agents (mostly rituximab) in 21 cases (25.9%). Despite marked interstitial fibrosis at initial biopsy, kidney function improved significantly during the 12-month period following diagnosis (final eGFR 49.9 vs 39.8 ml/min/1.73 m 2 at baseline, P < 0.001). No proven benefit of immunosuppressive agents over steroid therapy alone was found in this study.

Conclusion.

Renal involvement of pSS is mostly due to TIN with marked T, B and especially plasma cell infiltration. Renal dysfunction is usually isolated but can be severe. Use of CSs can improve the eGFR, but further studies are needed to define the best therapeutic strategy in this disease.

Glutathione S Transferases Polymorphisms Are Independent Prognostic Factors in Lupus Nephritis Treated with Cyclophosphamide

OBJECTIVE

To investigate association between genetic polymorphisms of GST, CYP and renal outcome or occurrence of adverse drug reactions (ADRs) in lupus nephritis (LN) treated with cyclophosphamide (CYC). CYC, as a pro-drug, requires bioactivation through multiple hepatic cytochrome P450s and glutathione S transferases (GST).

METHODS

We carried out a multicentric retrospective study including 70 patients with proliferative LN treated with CYC. Patients were genotyped for polymorphisms of the CYP2B6, CYP2C19, GSTP1, GSTM1 and GSTT1 genes. Complete remission (CR) was defined as proteinuria ≤0.33g/day and serum creatinine ≤124 µmol/l. Partial remission (PR) was defined as proteinuria ≤1.5g/day with a 50% decrease of the baseline proteinuria value and serum creatinine no greater than 25% above baseline.

RESULTS

Most patients were women (84%) and 77% were Caucasian. The mean age at LN diagnosis was 41 ± 10 years. The frequency of patients carrying the GST null genotype GSTT1-, GSTM1-, and the Ile→105Val GSTP1 genotype were respectively 38%, 60% and 44%. In multivariate analysis, the Ile→105Val GSTP1 genotype was an independent factor of poor renal outcome (achievement of CR or PR) (OR = 5.01 95% CI [1.02-24.51]) and the sole factor that influenced occurrence of ADRs was the GSTM1 null genotype (OR = 3.34 95% CI [1.064-10.58]). No association between polymorphisms of cytochrome P450s gene and efficacy or ADRs was observed.

CONCLUSION

This study suggests that GST polymorphisms highly impact renal outcome and occurrence of ADRs related to CYC in LN patients.

Spectrum and Prognosis of Noninfectious Renal Mixed Cryoglobulinemic GN

Noninfectious mixed cryoglobulinemic GN (MCGN) has been poorly investigated. We analyzed presentation and outcome of 80 patients with biopsy-proven MCGN, which were identified in the retrospective French CryoVas survey. MCGN was related to primary Sjögren's syndrome in 22.5% of patients and to lymphoproliferative disorders in 28.7% of patients, and was defined as essential in 48.8% of patients. At presentation, hematuria, proteinuria ≥1 g/d, hypertension, and renal failure were observed in 97.4%, 84.8%, 85.3%, and 82.3% of cases, respectively. Mean±eGFR was 39.5±20.4 ml/min per 1.73 m(2) Membranoproliferative GN was the predominant histologic pattern, observed in 89.6% of cases. Renal interstitium inflammatory infiltrates were observed in 50% of cases. First-line treatment consisted of steroids alone (27.6%) or in association with rituximab (21.1%), alkylating agents (36.8%) or a combination of cyclophosphamide and rituximab (10.5%). After a mean follow-up of 49.9±45.5 months, 42.7% of patients relapsed with a renal flare in 75% of cases. At last follow-up, mean eGFR was 50.2±26.1 ml/min per 1.73 m(2)with 9% of patients having reached ESRD; 59% and 50% of patients achieved complete clinical and renal remission, respectively. A rituximab+steroids regimen prevented relapses more effectively than steroids alone or a cyclophosphamide+steroids combination did, but was associated with a higher rate of early death when used as first-line therapy. Severe infections and new-onset B-cell lymphoma occurred in 29.1% and 8.9% of cases, respectively; 24% of patients died. In conclusion, noninfectious MCGN has a poor long-term outcome with severe infections as the main cause of death.

Mutation Update of the CLCN5 Gene Responsible for Dent Disease 1

Dent disease is a rare X-linked tubulopathy characterized by low molecular weight proteinuria, hypercalciuria, nephrocalcinosis and/or nephrolithiasis, progressive renal failure, and variable manifestations of other proximal tubule dysfunctions. It often progresses over a few decades to chronic renal insufficiency, and therefore molecular characterization is important to allow appropriate genetic counseling. Two genetic subtypes have been described to date: Dent disease 1 is caused by mutations of the CLCN5 gene, coding for the chloride/proton exchanger ClC-5; and Dent disease 2 by mutations of the OCRL gene, coding for the inositol polyphosphate 5-phosphatase OCRL-1. Herein, we review previously reported mutations (n = 192) and their associated phenotype in 377 male patients with Dent disease 1 and describe phenotype and novel (n = 42) and recurrent mutations (n = 24) in a large cohort of 117 Dent disease 1 patients belonging to 90 families. The novel missense and in-frame mutations described were mapped onto a three-dimensional homology model of the ClC-5 protein. This analysis suggests that these mutations affect the dimerization process, helix stability, or transport. The phenotype of our cohort patients supports and extends the phenotype that has been reported in smaller studies.

Treatment of systemic necrotizing vasculitides in patients aged sixty-five years or older: results of a multicenter, open-label, randomized controlled trial of corticosteroid and cyclophosphamide-based induction therapy

OBJECTIVE

To investigate a new therapeutic strategy, with rapid corticosteroid dose tapering and limited cyclophosphamide (CYC) exposure, for older patients with systemic necrotizing vasculitides (SNVs; polyarteritis nodosa [PAN], granulomatosis with polyangiitis [Wegnener's] [GPA], microscopic polyangiitis [MPA], or eosinophilic GPA [Churg-Strauss] [EGPA]).

METHODS

A multicenter, open-label, randomized controlled trial comprising patients ≥65 years old and newly diagnosed as having SNV was conducted. The experimental treatment consisted of corticosteroids for ∼9 months and a maximum of six 500-mg fixed-dose intravenous (IV) CYC pulses, every 2-3 weeks, then maintenance azathioprine or methotrexate. The control treatment included ∼26 months of corticosteroids for all patients, combined with 500 mg/m(2) IV CYC pulses, every 2-3 weeks until remission, then maintenance for all patients with GPA or MPA and for those with EGPA or PAN with a Five-Factors Score (FFS) of ≥1. Randomization used a 1:1 ratio computer-generated list and was performed centrally with sealed opaque envelopes. The primary outcome measure was ≥1 serious adverse event (SAE) occurring within 3 years of followup. Secondary outcome measures included remission and relapse rates.

RESULTS

Among the 108 patients randomized, 4 were excluded (early consent withdrawal or protocol violation). Mean ± SD age at diagnosis was 75.2 ± 6.3 years. Analysis at 3 years included 53 patients (21 GPA, 21 MPA, 8 EGPA, and 3 PAN) in the experimental arm and 51 patients (15 GPA, 23 MPA, 6 EGPA, and 7 PAN) in the conventional arm. In total, 32 (60%) versus 40 (78%) had ≥1 SAE (P = 0.04), most frequently infections; 6 (11%) versus 7 (14%) failed to achieve remission (P = 0.71); 9 (17%) versus 12 (24%) died (P = 0.41); and 20 (44%) of 45 versus 12 (29%) of 41 survivors in remission experienced a relapse (P = 0.15).

CONCLUSION

For older SNV patients, an induction regimen limiting corticosteroid exposure and with fixed low-dose IV CYC pulses reduces SAEs in comparison to conventional therapy, and does not affect the remission rate. Three-year relapse rates remain high for both arms.

High prevalence of infectious events in thrombotic thrombocytopenic purpura and genetic relationship with toll-like receptor 9 polymorphisms: experience of the French Thrombotic Microangiopathies Reference Center

BACKGROUND

Infectious events have been reported as major environmental triggers of thrombotic thrombocytopenic purpura (TTP). We detail here the potential association between infections and TTP.

STUDY DESIGN AND METHODS

We recruited randomly and prospectively a cohort of 280 consecutive TTP patients during a 9-year period. Features of infection were systematically recorded.

RESULTS

Features consistent with an infectious event were observed in 114 patients (41%) at time of TTP diagnosis. Infectious agents were documented in 34 cases and were mainly Gram-negative bacilli. At time of diagnosis infected patients more frequently had fever (p < 0.001). Infections at diagnosis did not impact prognosis and outcome. Thirty-six percent of patients experienced an infectious event during hospitalization, which resulted in more exacerbation of TTP (p = 0.02). Infections were not overrepresented during treatment in patients who received steroids and/or rituximab. Further genetic analysis of toll-like receptor (TLR)-9 functionally relevant polymorphisms revealed that TLR-9 +2848 G and TLR-9 +1174 A genotypes were more frequent in TTP patients than in controls (p = 0.04 and p = 0.026, respectively) and more particularly in patients negative for the Class II human leukocyte antigen system susceptibility allele DRB1*11 (p = 0.001 and p = 0.002, respectively). Haplotypes estimation showed that 1174A-2848G haplotype was significantly more frequent in TTP (p = 0.004), suggesting a primary role for this haplotype variation in conferring a predisposition for acquired TTP.

CONCLUSION

Infections should be considered as an aggravating factor during the course of TTP. Particular polymorphisms in TLR-9 gene may represent risk factors for TTP.

Clinicopathological study of glomerular diseases associated with sarcoidosis: a multicenter study

Background

The association between sarcoidosis and glomerular diseases has not been extensively investigated in a large series and the potential features of this uncommon association remain to be determined.

Methods

We retrospectively identified 26 patients with biopsy-proven glomerular lesions that occurred in a sarcoidosis context. Potential remission of glomerular disease and sarcoidosis under specific treatment (steroid and/or immunosuppressive agents) was recorded for all patients. Demographic, clinical and biological characteristics were assessed at the time of kidney biopsy for each patient. Therapeutic data were analyzed for all patients.

Results

Glomerular disease occurred after the diagnosis of sarcoidosis in 11 of 26 cases (42%) (mean delay of 9.7 years). In six patients (23%), the glomerulopathy preceded the sarcoidosis diagnosis (mean delay 8 years). In the last nine patients (35%), both conditions occurred simultaneously. The most frequent glomerular disease occurring in sarcoidosis patients was membranous nephropathy in eleven cases. Other glomerular lesions included IgA nephropathy in six cases, focal segmental glomerulosclerosis in four patients, minimal change nephrotic syndrome for three patients and proliferative lupus nephritis in two patients. Granulomatous interstitial nephritis was associated with glomerular disease in six patients and was exclusively found in patients in whom the both disease occurred simultaneously. In nine patients with simultaneous glomerular and sarcoidosis diseases, we observed a strong dissociation between glomerular disease and sarcoidosis in terms of steroid responsiveness. At the end of the follow-up (mean of 8.4 years), six patients had reached end-stage renal disease and three patients had died.

Conclusions

A wide spectrum of glomerular lesions is associated with sarcoidosis. The close temporal relationship observed in some patients suggests common causative molecular mechanisms of glomerular injury but complete remission of both diseases in response to exclusive steroid therapy is infrequent.

Systemic vasculitis during the course of systemic sclerosis: report of 12 cases and review of the literature

Although the presence of antineutrophil cytoplasmic antibodies (ANCA) has been reported in patients with systemic sclerosis (SSc), the association of SSc and systemic vasculitis has rarely been described. We obtained information on cases of systemic vasculitis associated with SSc in France from the French Vasculitis Study Group and all members of the French Research Group on Systemic Sclerosis. We identified 12 patients with systemic vasculitis associated with SSc: 9 with ANCA-associated systemic vasculitis (AASV) and 3 with mixed cryoglobulinemia vasculitis (MCV). In all AASV patients, SSc was of the limited type. The main complication of SSc was pulmonary fibrosis. Only 2 patients underwent a D-penicillamine regimen before the occurrence of AASV. The characteristics of AASV were microscopic polyangiitis (n = 7) and renal limited vasculitis (n = 2). Anti-myeloperoxidase antibodies were found in 8 of the 9 patients. The Five Factor Score was above 1 in 3 of the 9 patients. Of the 3 patients with MCV, Sjögren syndrome was confirmed in 2. We compared our findings with the results of a literature review (42 previously reported cases of AASV with SSc). Although rare, vasculitis is a complication of SSc. AASV is the most frequent type, and its diagnosis can be challenging when the kidney is injured. Better awareness of this rare association could facilitate earlier diagnosis and appropriate management to reduce damage.

Development and validation of a predictive model for death in acquired severe ADAMTS13 deficiency-associated idiopathic thrombotic thrombocytopenic purpura: the French TMA Reference Center experience

BACKGROUND

Acquired thrombotic thrombocytopenic purpura is still associated with a 10-20% death rate. It has still not been possible to clearly identify early prognostic factors of death. This study involved thrombotic thrombocytopenic purpura patients with acquired severe (<10% of normal activity) ADAMTS13 deficiency and aimed to identify prognostic factors associated with 30-day death.

DESIGN AND METHODS

The study involved a prospective cohort of patients and was carried out between October 2000 and August 2010. A validation cohort of patients was set up from September 2010 to August 2011. Altogether, 281 (analysis cohort) and 66 (validation cohort) consecutive adult thrombotic thrombocytopenic purpura patients with acquired severe ADAMTS13 deficiency were enrolled. The study evaluated 30-day mortality after treatment initiation according to characteristics at inclusion.

RESULTS

Non-survivors (11%) were older (P=10(-6)) and more frequently presented arterial hypertension (P=5.10(-4)) and ischemic heart disease (P=0.013). Prognosis was increasingly poor with age (P=0.004). On presentation, cerebral manifestations were more frequent in non-survivors (P=0.018) and serum creatinine level was higher (P=0.008). The most significant independent variables determining death were age, severe cerebral involvement and LDH level 10 N or over. A 3-level risk score for early death was defined and confirmed in the validation cohort using these variables, with higher values corresponding to increased risk of early death.

CONCLUSIONS

A risk score for early death was defined in patients with thrombotic thrombocytopenic purpura and validated on an independent cohort. This score should help to stratify early treatment and identify patients with a worse prognosis.

Update of PAX2 mutations in renal coloboma syndrome and establishment of a locus-specific database

Renal coloboma syndrome, also known as papillorenal syndrome is an autosomal-dominant disorder characterized by ocular and renal malformations. Mutations in the paired-box gene, PAX2, have been identified in approximately half of individuals with classic findings of renal hypoplasia/dysplasia and abnormalities of the optic nerve. Prior to 2011, there was no actively maintained locus-specific database (LSDB) cataloguing the extent of genetic variation in the PAX2 gene and phenotypic variation in individuals with renal coloboma syndrome. Review of published cases and the collective diagnostic experience of three laboratories in the United States, France, and New Zealand identified 55 unique mutations in 173 individuals from 86 families. The three clinical laboratories participating in this collaboration contributed 28 novel variations in 68 individuals in 33 families, which represent a 50% increase in the number of variations, patients, and families published in the medical literature. An LSDB was created using the Leiden Open Variation Database platform: www.lovd.nl/PAX2. The most common findings reported in this series were abnormal renal structure or function (92% of individuals), ophthalmological abnormalities (77% of individuals), and hearing loss (7% of individuals). Additional clinical findings and genetic counseling implications are discussed.

[Renal disease in ANCA-associated vasculitis]

Renal disease in ANCA-associated vasculitis (AAV) is characterized by a pauci-immune necrotizing glomerulonephritis. Renal biopsy is essential for diagnosis, treatment strategy and also for the long-term prognosis of AAV. The prospective randomized trials conducted by the EUVAS and GFEV have contributed to define therapeutic guidelines. The current standard of care can be divided into two phases: initial immunosuppression for rapid and effective onset of remission and subsequent maintenance therapy to prevent relapses. Despite these recent therapeutic advances, mortality and morbidity, such as end-stage renal failure, remain high, related to diagnosis delay, drug-related toxicity, refractory disease and propensity of AAV to relapse. Conventional therapies need to be optimized, especially in high-risk patients. Targeting B-cells with rituximab is a new and attractive therapeutic option, but long term benefits and safety are still unknown.

Phenotype-genotype correlation and follow-up in adult patients with hypokalaemia of renal origin suggesting Gitelman syndrome

INTRODUCTION

Gitelman syndrome (GS) is a tubulopathy caused by SLC12A3 gene mutations, which lead to hypokalaemic alkalosis, secondary hyperaldosteronism, hypomagnesaemia and hypocalciuria.

AIM

The aim of this study was to assess the prevalence of SLC12A3 gene mutations in adult hypokalaemic patients; to compare the phenotype of homozygous, heterozygous and non-mutated patients; and to determine the efficiency of treatment.

METHODS

Clinical, biological and genetic data were recorded in 26 patients.

RESULTS

Screening for the SLC12A3 gene detected two mutations in 15 patients (six homozygous and nine compound heterozygous), one mutation in six patients and no mutation in five patients. There was no statistical difference in clinical symptoms at diagnosis between the three groups. Systolic blood pressure tended to be lower in patients with two mutations (P=0.16). Hypertension was unexpectedly detected in four patients. Five patients with two mutated alleles and two with heterozygosity had severe manifestations of GS. Significant differences were observed between the three groups in blood potassium, chloride, magnesium, supine aldosterone, 24 h urine chloride and magnesium levels and in modification of the diet in renal disease. Mean blood potassium levels increased from 2.8 ± 0.3, 3.5 ± 0.5 and 3.2 ± 0.3 before treatment to 3.2 ± 0.5, 3.7 ± 0.6 and 3.7 ± 0.3 mmol/l with treatment in groups with two (P=0.003), one and no mutated alleles respectively.

CONCLUSION

In adult patients referred for renal hypokalaemia, we confirmed the presence of mutations of the SLC12A3 gene in 80% of cases. GS was more severe in patients with two mutated alleles than in those with one or no mutated alleles. High blood pressure should not rule out the diagnosis, especially in older patients.

[Renal malakoplakia: an underestimate cause of renal failure]

Malakoplakia is an inflammatory granulomatous disease induced by defective phagocytic activity of macrophage. Malakoplakia is histologically characterized by the presence of Michaelis-Gutmann bodies in macrophages. Although not uncommon in the genito-urinary tract, isolated malakoplakia of the kidney is rarely found. Its main clinical presentation associates acute renal failure and acute pyelonephritis. The clue for diagnosis of renal malakoplakia is based on renal biopsy showing Michaelis-Gutmann bodies. Establishing the diagnosis of renal malakoplakia is essential as it determines the choice of antibiotics and duration of treatment. Prognosis remains poor, leading frequently to chronic renal failure. In this paper, we report four cases of renal malakoplakia and discuss clinical presentation, biological and pathological features, treatment and prognosis of this disease.

Predictive features of severe acquired ADAMTS13 deficiency in idiopathic thrombotic microangiopathies: the French TMA reference center experience

Severe ADAMTS13 deficiency occurs in 13% to 75% of thrombotic microangiopathies (TMA). In this context, the early identification of a severe, antibody-mediated, ADAMTS13 deficiency may allow to start targeted therapies such as B-lymphocytes-depleting monoclonal antibodies. To date, assays exploring ADAMTS13 activity require skill and are limited to only some specialized reference laboratories, given the very low incidence of the disease. To identify clinical features which may allow to predict rapidly an acquired ADAMTS13 deficiency, we performed a cross-sectional analysis of our national registry from 2000 to 2007. The clinical presentation of 160 patients with TMA and acquired ADAMTS13 deficiency was compared with that of 54 patients with detectable ADAMTS13 activity. ADAMTS13 deficiency was associated with more relapses during treatment and with a good renal prognosis. Patients with acquired ADAMTS13 deficiency had platelet count <30×10⁹/L (adjusted odds ratio [OR] 9.1, 95% confidence interval [CI] 3.4–24.2, P<.001), serum creatinine level ≤200 µmol/L (OR 23.4, 95% CI 8.8–62.5, P<.001), and detectable antinuclear antibodies (OR 2.8, 95% CI 1.0–8.0, P<.05). When at least 1 criteria was met, patients with a severe acquired ADAMTS13 deficiency were identified with positive predictive value of 85%, negative predictive value of 93.3%, sensitivity of 98.8%, and specificity of 48.1%. Our criteria should be useful to identify rapidly newly diagnosed patients with an acquired ADAMTS13 deficiency to better tailor treatment for different pathophysiological groups.

Clinical and morphologic spectrum of renal involvement in patients with mixed cryoglobulinemia without evidence of hepatitis C virus infection

Hepatitis C virus (HCV) infection represents, by far, the major cause of mixed cryoglobulinemia (MC). The renal disease associated with this pathological condition is now well described. By contrast, renal involvement in patients with MC not associated with HCV has been only poorly described, and few cases have been reported. We analyzed the demographic, clinical, and laboratory features and outcome in patients presenting with renal disease associated with MC not related to HCV infection. Records of 20 patients with MC and renal disease, with no evidence of HCV by serology and polymerase chain reaction analysis, were retrospectively analyzed. Renal biopsies and extensive searches for lymphoproliferative disorder were performed in all patients at presentation. MC was related to primary Sjögren Syndrome (pSS) in 9 patients, and to non-Hodgkin lymphoma in 1 patient, while MC was classified as essential in the remaining 10 cases. Renal involvement was characterized by microscopic hematuria in all patients, nephrotic range proteinuria in 75% of patients, hypertension in 80% of patients, and renal failure in 85% of patients (mean glomerular filtration rate, 46 mL/min per 1.73 m). Membranoproliferative glomerulonephritis with subendothelial deposits was observed in all kidney specimens. Skin vasculitis was the main extrarenal manifestation. In all patients, cryoglobulinemia was classified as type II MC, characterized by monoclonal IgMkappa and polyclonal IgG. Most patients (17/20) were treated with steroids or immunosuppressive agents, or both. Initial renal remission was observed in 94% of patients. However, renal relapse occurred in most patients, with 10% reaching end-stage renal disease. Three patients with essential MC developed B-cell lymphoma 36-48 months after the diagnosis of MC. Unexpectedly, B-cell lymphoma induced by Epstein-Barr virus infection occurred in only 1 of the 9 pSS patients. Forty percent of patients died as a result of extrarenal causes.Renal disease associated with MC unrelated to HCV is characterized by the high prevalence of pSS (45%), the finding of CD20+ B-lymphocyte nodular infiltrates in the kidney interstitium, and a high incidence of overt B-cell lymphoma during follow-up. These findings emphasize the need for repetitive clinical evaluation in those patients.

Thrombotic microangiopathy in adult Still's disease

Adult Still's disease (ASD) is a rare systemic disorder characterized by fever, arthralgia, cutaneous rash, and lymphadenopathy, with high polymorphonuclear leucocytosis and low glycosylated ferritinaemia. Kidney involvement has been reported rarely. We present a patient with ASD who developed haemolytic uraemic syndrome (HUS). The 42-year-old patient was admitted for unexplained fever related to ASD according to Yamaguchi's classification criteria. As Still's disease was resistant to prednisone, high-dose intravenous immunoglobulins (IV Ig) were administered. During the follow-up the patient developed acute renal failure and non-immune haemolytic anaemia with high levels of antiphospholipid antibodies (IgG anticardiolipin antibodies and anti-beta2 glycoprotein 1 antibodies). Renal biopsy disclosed thrombotic microangiopathy (TMA) with arteriolar and glomerular involvement. Treatment with steroids and intravenous IV Ig was reinitiated but renal function worsened towards end-stage renal failure. In this case, we suggest that antiphospholipid antibodies could have promoted arteriolar and glomerular TMA. HUS may be the cause of acute renal failure in Still's disease.

Pulse versus daily oral cyclophosphamide for induction of remission in antineutrophil cytoplasmic antibody-associated vasculitis: a randomized trial

BACKGROUND

Current therapies for antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis are limited by toxicity.

OBJECTIVE

To compare pulse cyclophosphamide with daily oral cyclophosphamide for induction of remission.

DESIGN

Randomized, controlled trial. Random assignments were computer-generated; allocation was concealed by faxing centralized treatment assignment to providers at the time of enrollment. Patients, investigators, and assessors of outcomes were not blinded to assignment.

SETTING

42 centers in 12 European countries.

PATIENTS

149 patients who had newly diagnosed generalized ANCA-associated vasculitis with renal involvement but not immediately life-threatening disease.

INTERVENTION

Pulse cyclophosphamide, 15 mg/kg every 2 to 3 weeks (76 patients), or daily oral cyclophosphamide, 2 mg/kg per day (73 patients), plus prednisolone.

MEASUREMENT

Time to remission (primary outcome); change in renal function, adverse events, and cumulative dose of cyclophosphamide (secondary outcomes).

RESULTS

Groups did not differ in time to remission (hazard ratio, 1.098 [95% CI, 0.78 to 1.55]; P = 0.59) or proportion of patients who achieved remission at 9 months (88.1% vs. 87.7%). Thirteen patients in the pulse group and 6 in the daily oral group achieved remission by 9 months and subsequently had relapse. Absolute cumulative cyclophosphamide dose in the daily oral group was greater than that in the pulse group (15.9 g [interquartile range, 11 to 22.5 g] vs. 8.2 g [interquartile range, 5.95 to 10.55 g]; P < 0.001). The pulse group had a lower rate of leukopenia (hazard ratio, 0.41 [CI, 0.23 to 0.71]).

LIMITATIONS

The study was not powered to detect a difference in relapse rates between the 2 groups. Duration of follow-up was limited.

CONCLUSION

The pulse cyclophosphamide regimen induced remission of ANCA-associated vasculitis as well as the daily oral regimen at a reduced cumulative cyclophosphamide dose and caused fewer cases of leukopenia.

PRIMARY FUNDING SOURCE

The European Union.

Renal lesions associated with IgM-secreting monoclonal proliferations: revisiting the disease spectrum

BACKGROUND AND OBJECTIVES

Since the first description of pathology of the kidney in Waldenström disease in 1970, there have been few reports on kidney complications of IgM-secreting monoclonal proliferations. Here, we aimed to revisit the spectrum of renal lesions occurring in patients with a serum monoclonal IgM.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Fourteen patients with a circulating monoclonal IgM and a kidney disease related to B cell proliferation were identified retrospectively. Demographic, clinical, and laboratory data were assessed for each patient at the time of kidney biopsy.

RESULTS

Seven patients had a nephrotic syndrome. Patients without nephrotic syndrome all had impaired renal function. Mean serum creatinine was 238 micromol/L. For five patients, the diagnosis of monoclonal IgM preceded the kidney disease by 28.8 mo (range 12 to 60). Seven patients had Waldenström disease, two had a small B cell non-Hodgkin lymphoma, one had an IgM-excreting multiple myeloma, one had a marginal zone B cell lymphoma, and three had an IgM-related disorder. Renal lesions included (1) intracapillary monoclonal deposits disease with granular, electron-dense IgM thrombi occluding capillary lumens (5); (2) atypical membranoproliferative glomerulonephritis (3); (3) lambda light chain amyloidosis (2) associated with mu deposits in one patient; (4) acute tubular necrosis (1); and (5) CD20(+) lymphomatous infiltration (3). Remission of the nephrotic syndrome was attained in three of seven patients, and renal function improved after chemotherapy.

CONCLUSIONS

Although renal complications of IgM proliferations are rare, a wide spectrum of kidney lesions is observed, without correlation with the type of hematologic disorder.

Clinical and histological characteristics of renal AA amyloidosis: a retrospective study of 68 cases with a special interest to amyloid-associated inflammatory response

We retrospectively reviewed the clinicopathological features of a series of 68 renal AA amyloidosis observations collected between 1990 and 2005. The amyloidogenic disease was a chronic infection (40.8%), a chronic inflammation (38%), a tumor (9.9%), a hereditary disease (9.9%), or was undetermined in 1.4% of cases. Nephrotic syndrome and renal insufficiency were noted in 63.1% and 75% of patients, respectively. The distribution pattern of glomerular amyloid deposits was mesangial segmental (14.7%), mesangial nodular (26.5%), mesangiocapillary (32.3%), and hilar (26.5%). Glomerular form was observed in 80.9% of cases and vascular form in 19.1%. AA amyloidosis-related inflammation was noted in 30 patients (44.1%) and appeared as a multinucleated giant cell reaction (27.9%) or a glomerular inflammatory infiltrate (25%), including glomerular crescents (17.6%). At the end of follow-up, 26 patients (38.2%) showed end-stage renal disease. The clinical presentation of glomerular and vascular forms was distinct with a clear predominance of proteinuria in glomerular form. Inflammatory reaction was preferentially observed in biopsies with a codeposition of immunoglobulin chains and/or complement factors in AA amyloid deposits. The distribution pattern of glomerular amyloid deposits and glomerular inflammatory reaction were independent factors influencing proteinuria level. Tubular atrophy, abundance, and distribution pattern of glomerular amyloid deposits at the time of biopsy were independent predictors of renal outcome. In conclusion, the glomerular involvement appeared as the determining histological factor for clinical manifestations and outcome of renal AA amyloidosis. AA amyloidosis-related inflammation could partly result from an immune response directed against AA fibrils and could induce amyloid resolution and crescents.

Prognostic value of anti-ADAMTS 13 antibody features (Ig isotype, titer, and inhibitory effect) in a cohort of 35 adult French patients undergoing a first episode of thrombotic microangiopathy with undetectable ADAMTS 13 activity

To study both the pathophysiologic and the prognostic value of ADAMTS13 in thrombotic microangiopathies (TMAs), we enrolled a cohort of 35 adult patients combining a first acute episode of TMA, an undetectable (below 5%) ADAMTS13 activity in plasma, and no clinical background such as sepsis, cancer, HIV, and transplantation. All patients were treated by steroids and plasma exchange, and an 18-month follow-up was scheduled. Remission was obtained in 32 patients (91.4%), and 3 patients died (8.6%) after the first attack. At presentation, ADAMTS13 antigen was decreased in 32 patients (91.4%), an ADAMTS13 inhibitor was detectable in 31 patients (89%), and an anti-ADAMTS13 IgG/IgM/IgA was present in 33 patients (94%). The 3 decedent patients were characterized by the association of several anti-ADAMTS13 Ig isotypes, including very high IgA titers, while mortality was independent of the ADAMTS13 inhibitor titer. In survivors, ADAMTS13 activity in remission increased to levels above 15% in 19 patients (59%) but remained undetectable in 13 patients (41%). Six patients relapsed either once or twice (19%) during the follow-up. High levels of inhibitory anti-ADAMTS13 IgG at presentation were associated with the persistence of an undetectable ADAMTS13 activity in remission, the latter being predictive for relapses within an 18-month delay.

PON1, a new biomarker of cardiovascular disease, is low in patients with systemic vasculitis

OBJECTIVES

Because systemic vasculitis (SV) predisposes to atherosclerosis, and high-density lipoprotein (HDL) prevents atherosclerosis by "reverse cholesterol transport" and by inhibiting low-density lipoprotein (LDL) oxidation thanks to apolipoprotein A-I (Apo-AI) and paraoxonase 1 (PON1), we assessed whether LDL oxidation was increased in SV and associated with less PON1 activity.

METHODS

The sera of 33 patients with active SV (ASV), 32 in full remission of SV (RSV) and 20 healthy subjects (HS) were analyzed for C-reactive protein (CRP), high-sensitivity-CRP, lipids, lipoproteins, apolipoproteins, PON1 activity, LDL-immune complexes (LDL-IC), and auto-antibodies to oxidized-LDL (ox-LDL), and anticardiolipin antibodies.

RESULTS

CRP was higher in ASV than RSV and HS, and negatively correlated with HDL-cholesterol and Apo-AI. Autoantibodies to ox-LDL and highly oxidized malondialdehyde-LDL were higher in RSV than ASV and HS (P<0.05). LDL-IC titers were higher in ASV than RSV and HS (P<0.05). PON1 activity was lower in ASV and RSV than HS (P=0.02). A trend toward a negative correlation between basal PON1 activity and anti-MDA-LDL antibodies (P=0.06) was observed.

CONCLUSION

Inflammatory markers in SV were associated with a modified lipoprotein profile, which could lower PON1 activity and contribute to increased ox-LDL titers and accelerated atherosclerosis development.