Syndrome de Gitelman (données cliniques, pronostic et place du diagnostic moléculaire)

POITIERS-BU Médecine pharmacie (861942103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Posterior reversible encephalopathy induced by intravenous immunoglobulin.

International audienc

Venetoclax-Targeted Therapy in t(11;14) AL Amyloidosis Patients after Frontline Daratumumab and Cybord: A Retrospective Analysis from the French Amyloidosis Network

International audienc

[Renal disorders associated with monoclonal gammopathies: diagnostic and therapeutic progress].

International audienceVarious renal disorders are associated with monoclonal gammopathies, secondary to tissue deposition or precipitation of a monoclonal immunoglobulin (Ig) or a fragment thereof (isolated Ig light chain or heavy chain). They are classified according to the localization of renal lesions, either glomerular or tubular and to the pattern of ultrastructural organization of Ig deposits. Renal disease in monoclonal gammopathies may be isolated, or associated with various systemic symptoms particularly in AL amyloidosis, Randall-type monoclonal Ig deposition disease and monoclonal cryoglobulinemias. Except for myeloma cast nephropathy, which occurs in the setting of high-mass myeloma and is recognized after electrophoretic analysis of proteinuria and AL amyloidosis, which diagnosis is usually made after pathological examination of non-invasive tissue specimens (i.e. abdominal fat or minor salivary glands), a kidney biopsy is required to identify the other types of renal disorders associated with monoclonal gammopathies and to estimate renal prognosis. Renal pathological diagnosis is difficult and relies on careful examination of kidney biopsy samples, by light microscopy, immunofluorescence studies using conjugates specific for Ig light and heavy chains, IgG sub-classes and heavy chain constant domains and by electron microscopy. In some cases, additional studies are required to identify the nature of deposits, such as immuno-electron microscopy or mass spectrometric-based proteomic analysis after laser dissection. In patients with renal disorders related to Ig light chain precipitation or deposition (myeloma cast nephropathy, AL amyloidosis, Randall-type light chain deposition disease), measurement of serum free light chains at baseline and throughout follow-up is mandatory to evaluate clonal response to chemotherapy. A more than or equal to 50% decrease in serum free light chain levels is associated with increased renal and patient survival. In AL amyloidosis, serum levels of markers of cardiac disease (NT-proBNP and troponin) are also closely associated with prognosis. Efficient chemotherapy, tailored to the underlying plasma cell or lymphoproliferative disorder and adapted to renal function, should be promptly introduced, even in the absence of overt malignant haematological disease. Renal prognosis and patient survival (particularly in AL amyloidosis and cast nephropathy) are closely associated with the rapid achievement of an haematological response. The combination of melphalan plus dexamethasone (MDex) is currently used as first-line chemotherapy in systemic AL amyloidosis. Bortezomib-based regimens are commonly employed as first-line treatment in myeloma cast nephropathy and Randall-type monoclonal Ig deposition disease and as second line therapy in AL amyloidosis patients with advanced cardiomyopathy or refractory to previous chemotherapy. Solid organ transplantation (heart and kidney) should be considered in patients with AL amyloidosis or Randall-type monoclonal Ig deposition disease and advanced cardiac or renal failure. Prolonged graft and patient survival may be obtained, providing that recipients do not have other severe organ involvement or symptomatic myeloma and that haematological remission has been achieved with chemotherapy before or after organ transplantation

[Current treatment of AL amyloidosis].

International audienceSystemic AL amyloidosis is a rare complication of monoclonal gammopathies. Renal manifestations are frequent, mostly characterized by heavy proteinuria, with nephrotic syndrome and renal failure in more than half of the patients at diagnosis. Without treatment, median survival does not exceed 12 months. Amyloid heart disease and diffusion of amyloid deposits are associated with reduced survival. Treatment of systemic AL amyloidosis has been profoundly modified with the introduction of international criteria for the definition of organ involvement and hematologic response, and with the use of sensitive tests for the measurement of serum-free light chain levels. Melphalan plus dexamethasone is now established as the gold standard for first line treatment of systemic AL, with similar efficacy and reduced treatment-related mortality compared to high-dose therapy. Modern chemotherapy regimens, based on the use of novel agents such as bortezomib and lenalidomide, might further improve patient survival

Fanconi syndrome and chronic kidney disease in paroxysmal nocturnal hemoglobinuria: effect of eculizumab therapy.

International audienceThe association of Fanconi syndrome (FS) and chronic kidney disease (CKD) has been rarely described during the course of paroxysmal nocturnal hemoglobinuria (PNH). We report 2 patients with PNH and CKD associated with proximal tubule dysfunction, which manifested as full-blown FS in one case. In both patients, abnormal iron load within the kidneys was demonstrated by magnetic resonance imaging, which correlated with diffuse and numerous hemosiderin inclusions within proximal tubular cells. After 12 months, eculizumab treatment resulted in significant decrease in the kidney iron load in both cases. Glomerular filtration rate improved in one case and was stabilized in the other, in whom pretreatment kidney biopsy had shown severe extensive interstitial fibrosis. However, symptoms of proximal tubular dysfunction persisted in both patients. These data suggest that hemosiderin deposition in proximal tubules is probably an important mechanism involved in the development of FS, an under recognized and early manifestation of CKD in PNH. Prolonged treatment with eculizumab may improve long-term renal function in PNH patients with CKD

Tubulo-interstitial nephritis with Fanconi syndrome in Behçet disease.

International audienc

[New insights in the treatment of myeloma with renal failure].

International audienceRenal failure, mostly related to myeloma cast nephropathy (MCN), is a frequent complication of multiple myeloma (MM), which occurs in up to 50% of patients during the course of the disease. Persistent renal failure in MM is associated with poor survival. Treatment of MCN relies on urgent symptomatic measures (alkalinisation, rehydration, correction of hypercalcemia, and withdrawal of nephrotoxic drugs), with rapid introduction of chemotherapy to efficiently reduce the production of monoclonal light chains (LC). Recent studies suggest that, in patients with MM and severe renal failure due to MCN, rapid removal of circulating LC, through intensive hemodialysis sessions using a new generation high cut-off dialysis membrane, might result in dialysis withdrawal in most patients. If the development of intensive therapy and new efficient chemotherapy agents (thalidomide, bortezomib, lenalidomide) has transformed the care and prognosis of MM, the modalities and safety of these therapeutic regimens in patients with renal failure remain to be defined. The association of bortezomib with dexamethasone should be considered currently as first-line treatment in patients with MM and impaired renal function

Glomerulonephritis with isolated C3 deposits and monoclonal gammopathy: a fortuitous association?

International audienceBACKGROUND AND OBJECTIVES: Glomerular deposition of monoclonal Ig has been exceptionally described as the cause of membranoproliferative glomerulonephritis, through activation of the complement alternative pathway (CAP). DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We retrospectively studied six adults with monoclonal gammopathy and glomerulonephritis (GN) characterized by isolated C3 deposits. RESULTS: All patients presented with hematuria, associated with chronic renal failure and proteinuria in five patients, three of whom had nephrotic syndrome. Five patients had monoclonal gammopathy of undetermined significance and one had smoldering myeloma. The serum monoclonal IgG (κ four of six, λ two of six) was associated with light chain (LC) proteinuria in five patients. Four patients had low serum C3 and/or factor B levels. C4, factor H (CFH), and I protein levels were normal in five of five patients; none had detectable C3NeF. IgG anti-CFH activity was positive in one case. No mutations in CFH, CFI, and MCP genes were identified in four of four patients. Deposits were intramembranous, subepithelial, and mesangial by electron microscopy, and stained positive for C3 (six of six), properdin, and CFH (two of two) but negative for Ig LC and heavy chains, C4, and C1q (6/6) by immunofluorescence. Five patients progressed to end-stage renal disease over a median period of 47 months, despite chemotherapy in four patients. In one patient, monoclonal λLC deposits were observed on a follow-up kidney biopsy after 4 years. CONCLUSIONS: GN with isolated glomerular C3 deposits might represent an unusual complication of plasma cell dyscrasia, related to complement activation through an autoantibody activity of the monoclonal Ig against a CAP regulator protein

RNA-based immunoglobulin repertoire sequencing is a new tool for the management of monoclonal gammopathy of renal (kidney) significance

International audienceThe diagnostic approach of monoclonal gammopathy of renal significance is based on the detection of a monoclonal immunoglobulin in the blood and urine, and the identification of the underlying clone through bone marrow and/or peripheral blood cytologic and flow cytometry analysis. However, the monoclonal component and its corresponding clone may be undetectable using these routine techniques. Since clone identification is the cornerstone for guiding therapy and assessing disease response, more sensitive methods are required. We recently developed a high-throughput sequencing assay from bone marrow mRNA encoding immunoglobulins (RACE-RepSeq). This technique provides both full-length V(D)J region (variable, diversity and joining genes that generate unique receptors as antigen receptors) of the monoclonal immunoglobulin and the dominant immunoglobulin repertoire. This allows analysis of mutational patterns, immunoglobulin variable gene frequencies and diversity due to somatic hypermutation. Here, we evaluated the diagnostic performance of RACE-RepSeq in 16 patients with monoclonal-associated kidney lesions, and low serum monoclonal immunoglobulin and free light chain levels at diagnosis. Bone marrow immunohistochemical analysis was negative in all 11 patients so tested and 7 of 12 patients had no detectable clone matching the kidney deposits using flow cytometry analysis. By contrast, RACE-RepSeq detected a dominant clonal light chain sequence of matched isotype with respect to kidney deposits in all patients. Thus, high throughput mRNA sequencing appears highly sensitive to detect subtle clonal disorders in monoclonal gammopathy of renal significance and suggest this novel approach could help improve the management of this kidney disease