Monoclonal gammopathy in the setting of Pyoderma gangrenosum.

Pyoderma gangrenosum (PG) is a neutrophilic dermatosis characterized by ulcerative painful lesions with violaceous undermined borders. Up to 75% of PG cases develop in association with an underlying systemic disease. Monoclonal gammopathy is reportedly a concomitant condition with PG, with studies indicating immunoglobulin (Ig) A gammopathy as the most common. Whether gammopathy is associated with PG or is an incidental finding has been debated. We sought to investigate the association and characteristics of gammopathy in patients with PG. We retrospectively identified PG patients at our institution from 2010 to 2022 who were screened for plasma cell dyscrasia. Of 106 patients identified, 29 (27%) had a gammopathy; subtypes included IgA (41%), IgG (28%), and biclonal (IgA and IgG) (14%). Mean age was similar between those with and without gammopathy (60.7 vs. 55.9 years; P = .26). In addition, hematologic or solid organ cancer developed in significantly more patients with vs. without gammopathy (8/29 [28%] vs. 5/77 [6%]; P = .003). Among the subtypes of gammopathy, IgG monoclonal gammopathy had the highest proportion of patients with subsequent cancer development (4 of 8 patients, 50%). Study limitations include a retrospective, single-institution design with a limited number of patients. Overall, our data show a high prevalence of gammopathy in patients with PG; those patients additionally had an increased incidence of cancer, especially hematologic cancer.

Sjögren's disease activity associates with cardiovascular disease and monoclonal gammopathy: a university cohort study of disease activity and comorbidities.

BACKGROUND: We used the University of Wisconsin cohort to determine the extent to which the EULAR Sjögren's syndrome disease activity index (ESSDAI) was associated with comorbidities that contribute to mortality. METHODS: Our University of Wisconsin, Madison cohort had 111 patients with Sjögren's Disease (SjD) by 2016 ACR/EULAR criteria and 194 control patients with sicca. Our study was performed from March 1st, 2020 through April 1st, 2023. We collected data using a standardized collection tool, including components of the Charlson Comorbidity Index (CCI). Stratifying our SjD patients by ESSDAI < 5 and ESSDAI ≥ 5, we assessed differences in comorbidities associated with mortality. RESULTS: At time of SjD diagnosis, the ESSDAI ≥ 5 group had increased odds of peripheral vascular disease compared to controls (OR 10.17; 95% CI 1.18-87.87). Patients with a current ESSDAI ≥ 5 were more likely to have a myocardial infarction compared to controls (OR 9.87; 95% CI 1.17-83.49). SjD patients had increased prevalence of monoclonal gammopathy compared to controls (9.3% vs 0.5%, p < 0.001). SjD patients with high ESSDAI at diagnosis had greater prevalence of monoclonal gammopathy compared to the SjD patients with a low ESSDAI (16% vs 5%, p = .04). As reported elsewhere, the ESSDAI ≥ 5 group had increased odds of chronic pulmonary disease (OR 4.37; 95% CI 1.59-11.97). CONCLUSION: We found high ESSDAI scores were associated with worse cardiovascular outcomes, specifically peripheral vascular disease and myocardial infarction. Furthermore, monoclonal gammopathy was more frequent in SjD patients compared to sicca controls, supporting screening for monoclonal gammopathy in the appropriate clinical scenario. Key Points • High ESSDAI scores are associated with worse cardiovascular outcomes, specifically peripheral vascular disease and myocardial infarction. • Monoclonal gammopathy is more frequent in SjD patients than sicca controls, supporting screening for monoclonal gammopathy in the appropriate clinical scenario.

PARAKID: Navigating the relation between paraproteins and kidney lesions: A multi-center retrospective observational study.

INTRODUCTION: Monoclonal gammopathy is a heterogeneous group of disorders due to the clonal proliferation of immunoglobulin-producing plasma cells or B lymphocytes. Patients develop kidney disease not only due to malignant transformation but also due to the idiosyncratic properties of the M protein and the host factors. We aim to study the spectrum of kidney diseases in patients with paraproteinemia. MATERIALS AND METHODS: A retrospective observational study was performed at three tertiary care centers in Southern India. Kidney biopsies conducted in these three centers were reviewed from June 1, 2020 to November 30, 2022. All biopsies suggestive of monotypic immunoglobulin or light chain restriction were included in the study. RESULTS: A total of 122 patients were included in the study with an incidence of 2.4%. The mean age was 52.27 ± 13.27 years, and majority (63.1%) were males. AL amyloidosis was most common in the monoclonal gammopathy of renal significance (MGRS) group, and cast nephropathy was most common in the multiple myeloma (MM) group. On histopathology, 83.6% had a single lesion, followed by 14.8% with double lesion, and 1.6% with triple lesion. CONCLUSION: Paraproteinemia is associated with a myriad of kidney lesions. MGRS and MM are usually present in the 6th decade of life and beyond, while proliferative glomerulonephritis with monoclonal immunoglobulin deposits is more common in the younger age group. Older age group, high creatinine, hyperuricemia, hyperphosphatemia, presence of more than one lesion on kidney biopsy, and presence of cast nephropathy was significantly associated with the requirement of kidney replacement therapy.

Disease associations with monoclonal gammopathy of undetermined significance can only be evaluated using screened cohorts: results from the population-based iStopMM study.

Monoclonal gammopathy of undetermined significance (MGUS) is an asymptomatic precursor condition that precedes multiple myeloma and related disorders but has also been associated with other medical conditions. Since systematic screening is not recommended, MGUS is typically diagnosed due to underlying diseases and most cases are not diagnosed. Most previous studies on MGUS disease associations have been based on clinical cohorts, possibly resulting in selection bias. Here we estimate this selection bias by comparing clinically diagnosed and screened individuals with MGUS with regards to demographics, laboratory features, and comorbidities. A total of 75,422 participants in the Iceland Screens, Treats, or Prevents Multiple Myeloma (iStopMM) study were screened for MGUS by serum protein electrophoresis, immunofixation and free light chain assay (clinicaltrials gov. Identifier: NCT03327597). We identified 3,352 individuals with MGUS, whereof 240 had previously been clinically diagnosed (clinical MGUS), and crosslinked our data with large, nationwide registries for information on comorbidities. Those with clinical MGUS were more likely to have at least one comorbidity (odds ratio=2.24; 95% confidence interval: 1.30-4.19), and on average had more comorbidities than the screened MGUS group (3.23 vs. 2.36, mean difference 0.68; 95% confidence interval: 0.46-0.90). They were also more likely to have rheumatological disease, neurological disease, chronic kidney disease, liver disease, heart failure, or endocrine disorders. These findings indicate that individuals with clinical MGUS have more comorbidities than the general MGUS population and that previous studies have been affected by significant selection bias. Our findings highlight the importance of screening data when studying biological and epidemiological implications of MGUS.

[Monoclonal gammopathy of uncertain significance]. / Gammapatía monoclonal de significado incierto.

Monoclonal gammopathy of uncertain significance is a premalignant plasma cell neoplasm with a high prevalence in the population over 50 years of age and an annual risk of progression of 1%. Multiple recent studies have led to advances in understanding both the pathogenesis of these disorders and their risk of progression to other diseases. Patients require lifelong follow-up, and a multidisciplinary and risk-adapted approach is essential. In recent years, an increasing number of entities associated with a paraprotein, known as clinically significant monoclonal gammopathies, have been recognized.

Epidemiology of monoclonal gammopathy in Morocco - A hospital-based study.

BACKGROUND: Monoclonal gammopathies are a group of disorders associated with clonal proliferation of plasma cells that produces a monoclonal protein. AIMS: The main objective of this study was to describe the epidemiological and immunochemical characteristics of monoclonal gammopathies diagnosed during 19 years in a Moroccan teaching hospital. MATERIALS AND RESULTS: This retrospective study enrolled 443 Moroccan patients with monoclonal gammopathy, patients meeting the inclusion and exclusion criteria in at the biochemistry department of Military Hospital in Rabat, the capital of Morocco, from January 2000 to August 2019. Of the 443 enrolled patients, 320 (72.23%) were men and 123 (27.77%) were women. All patients were of Caucasian origin, from 12 Moroccan regions. The patient's samples were collected and subjected to serum protein electrophoresis and serum immunofixation electrophoresis to further characterize the monoclonal protein. The mean ± SD age of the 443 participants was 62.24 ± 13.14 years. Reasons for being admitted to the hospital were as follows, bone pain (41.60%), renal failure (19.08%), alteration of the general condition (12.21%), and anemia (10.69). Plasma cell proliferative disorders in our study were as follows, multiple myeloma (MM) (45.65%), Monoclonal gammopathies of undetermined significance (MGUS) (39.05%), Waldenstrom's macroglobulinemia (5.58%), Lymphoma (2.27% + 1.2%), Chronic Lymphocytic Leukemia (2.48%), Plasma cell leukemia (1.86%), Plasmacytoma (0.62%), POEMS syndrome (0.41%), and Amyloidosis (0.84%). The most frequent isotypes in MM were the IgGκ (62) 36.5%, IgGλ (52) 30.6%, IgAκ (27) 15.9%, and the IgAλ (19) 11.2%. It is also worth noting that Free light chain MM represents 20% of all cases of MM. CONCLUSIONS: We found that monoclonal gammopathies are age-related and affects men more than women, also the results of this study point to the delayed diagnosis of monoclonal gammopathies, since most of our patients were diagnosed at the MM stage. The most frequent isotypes were the IgGκ and IgGλ in MM and MGUS, in Waldenström macroglobulinemia were IgMκ and IgMλ and the oligoclonal profile represented only 3.70%.

Biclonal Gammopathies in South Tunisia: Clinical and Biological Characteristics.

OBJECTIVE: Biclonal gammopathies (BGs) are rare situations characterized by the production of 2 monoclonal proteins. There are no available data on BGs in North Africa. We aimed to estimate the prevalence of BGs in our population and describe their clinical and laboratory features. METHODS: We conducted a 31-year retrospective study including patients with persistent double monoclonal bands based on the results of immunofixation/immunoelectrophoresis. RESULTS: A total of 35 patients with available clinical data (sex ratio, M/F = 1.53; mean age, 70 ±â€…10.87 years [range, 45-90 years]) were included. The main associated conditions were multiple myeloma (MM) (40%), BG of undetermined significance (BGUS) (34%), and lymphoproliferative diseases (23%). Only one-third of the patients had 2 monoclonal spikes on serum protein electrophoresis. The most common paraprotein combinations were immunoglobulin (Ig)G-IgG (25%) and IgG-IgA (23%) with different light chains in one-half of the cases. The mean follow-up was 25.6 months (median, 12 months). No BGUS evolved into a malignant disease. CONCLUSION: BGs are rare in clinical laboratory routine but must be accurately identified by the pathologist. Our cohort is characterized by a high prevalence of BGUS compared with MM.

Prevalence of corneal findings and their interrelation with hematological findings in monoclonal gammopathy.

PURPOSE: To determine prevalence of paraproteinemic keratopathy (PPK) among patients with monoclonal gammopathy (MG). To evaluate interrelation between corneal and hematological parameters in patients with PPK. METHODS: Fifty-one patients with monoclonal gammopathy of undetermined significance (n = 19), smoldering multiple myeloma (n = 5) or multiple myeloma (n = 27) were prospectively included in this study. Best-corrected visual acuity, slit-lamp biomicroscopy, Scheimpflug tomography, in-vivo confocal laser scanning microscopy, optical coherence tomography and complete hematological workup were assessed. RESULTS: We identified n = 19 patients with bilateral corneal opacities compatible with PPK. PPK was newly diagnosed in 13 (29%) of 45 patients with a primary hematological diagnosis and in n = 6 patients without previous hematological diagnosis. The most common form was a discreet stromal flake-like PPK (n = 14 of 19). The median level of M-protein (p = 0.59), IgA (p = 0.53), IgG (p = 0.79) and IgM (p = 0.59) did not differ significantly between the patients with and without PPK. The median level of the FLC κ in serum of patients with kappa-restricted plasma cell dyscrasia was 209 mg/l in patients with PPK compared to 38.1 mg/l in patients without PPK (p = 0.18). Median level of FLC lambda in serum of patients with lambda-restricted plasma cell dyscrasia was lower in patients with PPK compared to patients without PPK (p = 0.02). CONCLUSION: The PPK was mostly discreet, but its prevalence (29%) was higher than expected. Median level of the monoclonal paraprotein was not significantly higher in patients with PPK compared to patients without PPK. Our results suggest a lack of correlation between morphology and severity of the ocular findings and severity of the monoclonal gammopathy. TRIAL REGISTRATION: German Clinical Trial Register: DRKS00023893.

Prevalence of Monoclonal Gammopathy of Undetermined Significance in Black South African Men.

BACKGROUND: Both multiple myeloma and its precursor, monoclonal gammopathy of undetermined significance (MGUS), occur twice as often within Black compared with White populations, suggesting that racial disparities lie within the development of MGUS. Nonetheless, MGUS has been studied mainly in White cohorts; the study that first described the natural history of MGUS was conducted in 97.3% White Olmsted County, Minnesota. METHODS: We determined the prevalence of MGUS among 386 Black South African (SA) men >30 years at Chris Hani Baragwanath Hospital in Johannesburg. We conducted serum protein electrophoresis and free light chain quantification to define MGUS by the same criteria as the Olmsted County studies. We also investigated the association between MGUS and various clinical factors, including human immunodeficiency virus (HIV) infection and smoking. RESULTS: We found the prevalence of MGUS to be 8.03% [95% confidence interval (CI), 5.32-10.74], nearly 1.6-fold higher than in the White Olmsted County male population. In a univariable logistic regression model, MGUS was associated with HIV status (OR, 2.39; 95% CI, 0.95-5.49), but in an adjusted model that included body mass index and cigarette use, the association was not statistically significant. Those who were current (vs. never) cigarette smokers were more likely to have MGUS in both univariable (OR, 5.60; 95% CI, 2.16-17.42) and multivariable models (OR, 4.49; 95% CI, 1.63-14.56). CONCLUSIONS: The prevalence of MGUS in Black SA men is substantially higher than in White populations and may be associated with HIV status and cigarette use. IMPACT: Racial disparities in MGUS exist and may be associated with potentially modifiable risk factors.

Prevalence and Clinical Characteristics of Paraproteinemia Associated with Chronic Myeloid Leukemia.

INTRODUCTION: Data regarding the prevalence of paraproteinemia in patients with chronic myeloid leukemia (CML) are lacking. METHODS: To evaluate for the prevalence of paraproteinemia, we undertook this cross-sectional study among consecutive chronic-phase CML patients. Complete blood count, chemistry, immunoglobulins, serum-free light chains, serum-protein electrophoresis and immunofixation were collected. Further analyses evaluated whether various patient-, disease-, and treatment-related variables are associated with paraproteinemia. RESULTS: One hundred patients, median age 63.5 (IQR 48.1-72) years were recruited. Median time from CML diagnosis to enrollment was 6.3 (IQR 2.3-11.3) years. Monoclonal protein was detected in 8 patients (8%), diagnosed with smoldering multiple myeloma (SMM, n = 2) and low-risk monoclonal gammopathy of undetermined significance (MGUS, n = 6). Six patients were on tyrosine kinase inhibitor treatment, 2 were in treatment-free remission. The only covariate associated with paraproteinemia was the presence of anemia, albeit with borderline statistical significance in univariate analysis (p = 0.053) and when adjusted for age (p = 0.056). CONCLUSIONS: In this largest study so far describing the prevalence of paraproteinemia among CML patients, we found MGUS prevalence to be higher than the 3.2% expected prevalence in the general population above 50 years and a non-negligible prevalence of SMM (2%). Screening for paraproteinemia in CML patients, especially in the presence of anemia, should be considered.

Body mass index associated with monoclonal gammopathy of undetermined significance (MGUS) progression in Olmsted County, Minnesota.

Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant clonal disorder that progresses to multiple myeloma (MM), or other plasma-cell or lymphoid disorders at a rate of 1%/year. We evaluate the contribution of body mass index (BMI) to MGUS progression beyond established clinical factors in a population-based study. We identified 594 MGUS through a population-based screening study in Olmsted County, Minnesota, between 1995 and 2003. Follow-up time was calculated from the date of MGUS to last follow-up, death, or progression to MM/another plasma-cell/lymphoid disorder. BMI (kg/m2 < 25/≥25) was measured close to screening date. We used Cox regression to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association of BMI ≥ 25 versus BMI < 25 with MGUS progression and also evaluated the corresponding c-statistic and 95% CI to describe discrimination of the model for MGUS progression. Median follow-up was 10.5 years (range:0-25), while 465 patients died and 57 progressed and developed MM (N = 39), AL amyloidosis (N = 8), lymphoma (N = 5), or Waldenstrom-macroglobulinemia (N = 5). In univariate analyses, BMI ≥ 25 (HR = 2.14,CI:1.05-4.36, P = 0.04), non-IgG (HR = 2.84, CI:1.68-4.80, P = 0.0001), high monoclonal (M) protein (HR = 2.57, CI:1.50-4.42, P = 0.001), and abnormal free light chain ratio (FLCr) (HR = 3.39, CI:1.98-5.82, P < 0.0001) were associated with increased risk of MGUS progression, and were independently associated in a multivariable model (c-statistic = 0.75, CI:0.68-0.82). The BMI association was stronger among females (HR = 3.55, CI:1.06-11.9, P = 0.04) vs. males (HR = 1.39, CI:0.57-3.36, P = 0.47), although the interaction between BMI and sex was not significant (P = 0.15). In conclusion, high BMI is a prognostic factor for MGUS progression, independent of isotype, M protein, and FLCr. This association may be stronger among females.

[Descriptive cross-sectional study assessing the clinical and paraclinic profiles of monoclonal gammopathies in an agricultural region of Souss-Massa, Morocco]. / Étude transversale descriptive sur les profils cliniques et paracliniques des gammapathies monoclonales au niveau d'une région agricole du Souss-Massa au Maroc.

Introduction: given the lack of information about monoclonal gammopathies, our primary study outcome was to describe the epidemiological, clinical and biochemical profiles of monoclonal gammopathies in the Souss-Massa region, in southern Morocco. Methods: we conducted a retrospective study, by selecting only complete medical records. We used records of patients diagnosed with monoclonal gammopathy at the local oncology center during a period of over 10 years. Results: one hundred and seventeen patients were included in the study, with a high male predominance (65%) and a male/female sex-ratio of 1.85. The average age of our study population was 61.44 (ET 14.54) years. Diagnoses (based on frequency) included: multiple myeloma 82.0% (n=96), solitary plasmacytoma 8.5% (n=10), monoclonal gammopathies of undetermined significance 2.6% (n=3), lymphoma 2.5% (n=3), secondary plasma cell leukaemia 1.7% (n=2), Waldenström´s disease 1.7%(n=2) and chronic lymphoid leukemia (n=1). The isotype distribution was as follows: IgG Kappa 33.7% (n=28), IgG lambda 21.7% (n=18), IgA Kappa 12.0% (n=10), IgA lambda 7.2% (n=6), IgM kappa 3.6% (n=3), and IgD lambda 2.4% (n=2). Biconal peak was reached in two cases, with a percentage of 2.4%. Conclusion: diagnostic delay was observed compared to international studies due to the unavailability of electrophoresis in the care structures.

Multi-trajectory models of serum biomarkers among patients with monoclonal gammopathy of undetermined significance.

Understanding the progression of monoclonal gammopathy of undetermined significance (MGUS) to multiple myeloma (MM) is needed to identify patients who would benefit from closer clinical surveillance. Given that two of the defining criteria of MM are renal failure and anemia, we described the trajectories of creatinine (Cr) and hemoglobin (Hgb) over time in patients with a diagnosis of MGUS. Patients diagnosed with MGUS (n = 424) were identified by a previously validated case-finding algorithm using health claims and electronic health record data (2007-2015) and followed through 2018. Group-based trajectory modeling identified patients with distinct laboratory value trajectories of Cr (mg/dl) and Hgb (g/dl). Most patients were non-Hispanic White (97.6%) with a mean age of 75 years at MGUS diagnosis. Three multi-trajectory groups were identified: (1) Normal Cr/Hgb (n = 225; 53.1%)-stable serum Cr levels and decreasing, normal Hgb levels; (2) Normal Cr/lower-normal Hgb group (n = 188; 44.3%)-stable, slightly elevated levels of Cr and decreasing levels of Hgb; and (3) High Cr/borderline Hgb group (n = 11; 2.6%)-increased Cr levels and stable low levels of Hgb. Patients with MGUS in Group 2 were older than patients in other groups, and patients in group 3 had more comorbidities than participants in all other groups. Few patients developed MM during the study period. We were able to identify distinct biomarker trajectories in patients with MGUS over time. Future research should investigate how these trajectories may be related to the risk of progression to MM, including M-protein levels.

Prevalence of monoclonal gammopathies and clinical outcomes in a high-risk US population screened by mass spectrometry: a multicentre cohort study.

BACKGROUND: Prevalence estimates for monoclonal gammopathy of undetermined significance (MGUS) are based on predominantly White study populations screened by serum protein electrophoresis supplemented with immunofixation electrophoresis. A prevalence of 3% is reported for MGUS in the general population of European ancestry aged 50 years or older. MGUS prevalence is two times higher in individuals of African descent or with a family history of conditions related to multiple myeloma. We aimed to evaluate the prevalence and clinical implications of monoclonal gammopathies in a high-risk US population screened by quantitative mass spectrometry. METHODS: We used quantitative matrix-assisted laser desorption ionisation-time of flight (MALDI-TOF) mass spectrometry and EXENT-iQ software to screen for and quantify monoclonal gammopathies in serum from 7622 individuals who consented to the PROMISE screening study between Feb 26, 2019, and Nov 4, 2021, and the Mass General Brigham Biobank (MGBB) between July 28, 2010, and July 1, 2021. M-protein concentrations at the monoclonal gammopathy of indeterminate potential (MGIP) level were confirmed by liquid chromatography mass spectrometry testing. 6305 (83%; 2211 from PROMISE, 4094 from MGBB) of 7622 participants in the cohorts were at high risk for developing a monoclonal gammopathy on the basis of Black race or a family history of haematological malignancies and fell within the eligible high-risk age range (30 years or older for PROMISE cohort and 18 years or older for MGBB cohort); those over 18 years were also eligible if they had two or more family members with a blood cancer (PROMISE cohort). Participants with a plasma cell malignancy diagnosed before screening were excluded. Longitudinal clinical data were available for MGBB participants with a median follow-up time from serum sample screening of 4·5 years (IQR 2·4-6·7). The PROMISE study is registered with ClinicalTrials.gov, NCT03689595. FINDINGS: The median age at time of screening was 56·0 years (IQR 46·8-64·1). 5013 (66%) of 7622 participants were female, 2570 (34%) male, and 39 (<1%) unknown. 2439 (32%) self-identified as Black, 4986 (65%) as White, 119 (2%) as other, and 78 (1%) unknown. Using serum protein electrophoresis with immunofixation electrophoresis, the MGUS prevalence was 6% (101 of 1714) in high-risk individuals aged 50 years or older. Using mass spectrometry, we observed a total prevalence of monoclonal gammopathies of 43% (1788 of 4207) in this group. We termed monoclonal gammopathies below the clinical immunofixation electrophoresis detection level (<0·2 g/L) MGIPs, to differentiate them from those with higher concentrations, termed mass-spectrometry MGUS, which had a 13% (592 of 4207) prevalence by mass spectrometry in high-risk individuals aged 50 years or older. MGIP was predominantly of immunoglobulin M isotype, and its prevalence increased with age (19% [488 of 2564] for individuals aged <50 years, 29% [1464 of 5058] for those aged ≥50 years, and 37% [347 of 946] for those aged ≥70 years). Mass-spectrometry MGUS prevalence increased with age (5% [127 of 2564] for individuals aged <50 years, 13% [678 of 5058] for those aged ≥50 years, and 18% [173 of 946] for those aged ≥70 years) and was higher in men (314 [12%] of 2570) compared with women (485 [10%] 5013; p=0·0002), whereas MGIP prevalence did not differ significantly by gender. In those aged 50 years or older, the prevalence of mass spectrometry was significantly higher in Black participants (224 [17%] of 1356) compared with the controls (p=0·0012) but not in those with family history (368 [13%] of 2851) compared with the controls (p=0·1008). Screen-detected monoclonal gammopathies correlated with increased all-cause mortality in MGBB participants (hazard ratio 1·55, 95% CI 1·16-2·08; p=0·0035). All monoclonal gammopathies were associated with an increased likelihood of comorbidities, including myocardial infarction (odds ratio 1·60, 95% CI 1·26-2·02; p=0·00016 for MGIP-high and 1·39, 1·07-1·80; p=0·015 for mass-spectrometry MGUS). INTERPRETATION: We detected a high prevalence of monoclonal gammopathies, including age-associated MGIP, and made more precise estimates of mass-spectrometry MGUS compared with conventional gel-based methods. The use of mass spectrometry also highlighted the potential hidden clinical significance of MGIP. Our study suggests the association of monoclonal gammopathies with a variety of clinical phenotypes and decreased overall survival. FUNDING: Stand Up To Cancer Dream Team, the Multiple Myeloma Research Foundation, and National Institutes of Health.

Complement Activation and Thrombotic Microangiopathy Associated With Monoclonal Gammopathy: A National French Case Series.

RATIONALE & OBJECTIVE: Hemolytic uremic syndrome (HUS), a thrombotic microangiopathy (TMA) with kidney involvement, is a rare condition in patients with monoclonal gammopathy. In the absence of known causes of TMA, the role of complement activation in endothelial injury in patients with monoclonal gammopathy remains unknown and was the focus of this investigation. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: We studied the 24 patients in the French national registry of HUS between 2000 and 2020 who had monoclonal gammopathy without other causes of secondary TMA. We provide the clinical histories and complement studies of these patients. FINDINGS: Monoclonal gammopathy-associated TMA with kidney involvement is estimated to be 10 times less frequent than adult atypical HUS (aHUS) in the French national registry. It is characterized by severe clinical features, with 17 of 24 patients requiring dialysis at disease onset, and with median renal survival of only 20 months. TMA-mediated extrarenal manifestations, particularly cutaneous and neurological involvement, were common and associated with poor overall prognosis. Complement studies identified low C3, normal C4, and high soluble C5b-9 levels in 33%, 100%, and 77% of tested patients, respectively, indicating a contribution of the alternative and terminal complement pathways in the pathophysiology of the disease. Genetic abnormalities in complement genes known to be associated with aHUS were found in only 3 of 17 (17%) who were tested. LIMITATIONS: Retrospective study without comparison group; limited number of patients, limited available blood samples. CONCLUSIONS: Within the spectrum of TMA, TMA associated with monoclonal gammopathy represents a distinct subset. Our findings suggest that HUS associated with monoclonal immunoglobulin is a complement-mediated disease akin to aHUS.

Immunotyping Provides Equivalent Results to Immunofixation in a Population with a High Prevalence of Monoclonal Gammopathies.

BACKGROUND: Serum immunofixation (IF) is a common laboratory test used to diagnose and monitor patients with monoclonal gammopathies. Similarly, immunotyping (IT) by capillary electrophoresis can confirm the presence of a monoclonal protein (M-protein) and determine its isotype. The goal of this study was to compare the ability of IT and IF to detect M-proteins. METHODS: IT and IF results for 1000 waste clinical serum samples were obtained. All results were interpreted blindly by reviewers who were experienced in each technique. Results were compared by band. Results were also compared to patient history to determine if the original clone was present. We determined the sensitivity of IT and IF alone and in combination with additional tests. Finally, we evaluated the impact of reviewer training on the sensitivity of IT. RESULTS: IT and IF were concordant in 721/773 (93%) samples with a history of an intact M-protein and in 143/172 (83%) samples with a history of a free light chain (FLC) M-protein. IF was significantly more sensitive than IT for the detection of FLC M-proteins (P < 0.0001). However, IF was not more sensitive than IT for detection of intact M-proteins (P = 0.1272) or when each test was combined with the FLC ratio or urine immunofixation (P = 0.2812 and P = 0.6171, respectively). Finally, after training, inexperienced reviewers improved their IT sensitivity by 19%. CONCLUSION: IT provides equivalent results to IF for the detection of monoclonal proteins. Training and experience are critical to the accurate interpretation of IT.

Polyneuropathy and monoclonal gammopathy of undetermined significance (MGUS); update of a clinical experience.

BACKGROUND AND PURPOSE: Polyneuropathies associated with monoclonal gammopathy of undetermined significance (MGUS) encompass a group of phenotypically and immunologically heterogeneous neuropathies. While the best characterized is that associated with anti-myelin glycoprotein (MAG) antibodies, there are phenotypical and immunological neuropathy variants that still lack a clear classification. We analyzed a significant number of patients, in order to better evaluate the distribution of neuropathy phenotypes and to look for some common characteristics. METHODS: Clinical, neurophysiological, and laboratory data from 87 consecutive MGUS patients with peripheral neuropathy were analyzed and compared among patient groups with different MGUS classes and autoantibody reactivity. RESULTS: Anti-MAG neuropathy cases account for the most homogeneous group with regard to clinical and neurophysiological findings. Patients with anti-gangliosides or sulfatide (GS) antibodies, despite a marked phenotype heterogeneity, still share several common features, including a younger age at diagnosis, a more severe disease, and a prompt and sustained response to both immunoglobulin and rituximab therapies, mostly requiring chronic administration of immune treatment. CONCLUSIONS: Although heterogeneous, MGUS-associated, anti-GS antibody positive neuropathies have important similar features possibly resulting from a similar biological background.