Recurrence of focal segmental glomerulosclerosis after renal transplantation in patients with mutations of podocin

A Review of Focal Segmental Glomerulosclerosis Classification With a Focus on Genetic Associations

Focal segmental glomerulosclerosis (FSGS) defines a distinct histologic pattern observed in kidney tissue that is linked to several distinct underlying causes, all converging on the common factor of podocyte injury. It presents a considerable challenge in terms of classification because of its varied underlying causes and the limited correlation between histopathology and clinical outcomes. Critically, precise nomenclature is key to describe and delineate the pathogenesis, subsequently guiding the selection of suitable and precision therapies. A proposed pathomechanism-based approach has been suggested for FSGS classification. This approach differentiates among primary, secondary, genetic, and undetermined causes, aiming to provide clarity. Genetic FSGS from monogenic mutations can emerge during childhood or adulthood, and it is advisable to conduct genetic testing in cases in which there is a family history of chronic kidney disease, nephrotic syndrome, or resistance to treatment. Genome-wide association studies have identified several genetic risk variants, such as those in apolipoprotein L1 (APOL1), that play a role in the development of FSGS. Currently, no specific treatments have been approved to treat genetic FSGS; however, interventions targeting underlying cofactor deficiencies have shown potential in some cases. Furthermore, encouraging results have emerged from a phase 2 trial investigating inaxaplin, a novel small molecule APOL1 channel inhibitor, in APOL1-associated FSGS.

Recurrent disease after pediatric renal transplantation

BACKGROUND

Recurrent disease after kidney transplant remains an important cause of allograft failure, accounting for 7-8% of graft loss and ranking as the fifth most common cause of allograft loss in the pediatric population. Although the pathophysiology of many recurrent diseases is incompletely understood, recent advances in basic science and therapeutics are improving outcomes and changing the course of several of these conditions.

METHODS

Review of the literature.

RESULTS

We discuss the diagnosis and management of recurrent disease.

CONCLUSION

We highlight new insights into the pathophysiology and treatment of post-transplant primary hyperoxaluria, focal segmental glomerulosclerosis, immune complex glomerulonephritis, C3 glomerulopathy, lupus nephritis, atypical hemolytic uremic syndrome, and IgA nephropathy.

Steroid-Resistant Nephrotic Syndrome due to NPHS2 Variants Is Not Associated With Posttransplant Recurrence

Introduction

Unlike idiopathic nephrotic syndrome (NS), hereditary podocytopathies are not expected to recur after kidney transplantation. However, some reports of posttransplant recurrence of NS in patients carrying variants in the NPHS2 gene have been described, notably with the p.Arg138Gln variant, which is more prevalent in Europe. The objective of this study was to assess the risk of recurrence after kidney transplantation in a large cohort of patients with biallelic NPHS2 pathogenic variants.

Methods

Since January 2010, 61 patients identified at Necker-Enfants Malades Hospital and 56 enrolled in the PodoNet Registry with biallelic variants in the NPHS2 gene were transplanted and were compared with 44 transplanted children with steroid-resistant NS (SRNS) without any identified pathogenic variant.

Results

Of the 117 patients, 23 carried the p.Arg138Gln variant in the homozygous state and 16 in the compound heterozygous state. The other 78 patients carried different variants in the homozygous (n = 44) or compound heterozygous state. Only 1 patient with NPHS2-related SRNS experienced posttransplant recurrence (median follow-up of cohort 8.5 years [2.5-15]). Conversely, 7 of 44 patients (16%) without any identified pathogenic variant recurred within a maximum of 7 days after transplantation (median follow-up 8.9 years [0.6-13.9]).

Conclusion

In this large cohort, the risk of patients with causative variants in the NPHS2 gene to develop NS recurrence after kidney transplantation was extremely low. This is coherent with the pathophysiology of intrinsic slit-diaphragm disease. These data are reassuring and should be considered when counselling patients, making living kidney donation, whether related or not, a safe choice.

Developing a genetic testing panel for evaluation of morbidities in kidney transplant recipients

Cardiovascular disease, infection, malignancy, and thromboembolism are major causes of morbidity and mortality in kidney transplant recipients (KTR). Prospectively identifying monogenic conditions associated with post-transplant complications may enable personalized management. Therefore, we developed a transplant morbidity panel (355 genes) associated with major post-transplant complications including cardiometabolic disorders, immunodeficiency, malignancy, and thrombophilia. This gene panel was then evaluated using exome sequencing data from 1590 KTR. Additionally, genes associated with monogenic kidney and genitourinary disorders along with American College of Medical Genetics (ACMG) secondary findings v3.2 were annotated. Altogether, diagnostic variants in 37 genes associated with Mendelian kidney and genitourinary disorders were detected in 9.9% (158/1590) of KTR; 25.9% (41/158) had not been clinically diagnosed. Moreover, the transplant morbidity gene panel detected diagnostic variants for 56 monogenic disorders in 9.1% KTRs (144/1590). Cardiovascular disease, malignancy, immunodeficiency, and thrombophilia variants were detected in 5.1% (81), 2.1% (34), 1.8% (29) and 0.2% (3) among 1590 KTRs, respectively. Concordant phenotypes were present in half of these cases. Reviewing implications for transplant care, these genetic findings would have allowed physicians to set specific risk factor targets in 6.3% (9/144), arrange intensive surveillance in 97.2% (140/144), utilize preventive measures in 13.2% (19/144), guide disease-specific therapy in 63.9% (92/144), initiate specialty referral in 90.3% (130/144) and alter immunosuppression in 56.9% (82/144). Thus, beyond diagnostic testing for kidney disorders, sequence annotation identified monogenic disorders associated with common post-transplant complications in 9.1% of KTR, with important clinical implications. Incorporating genetic diagnostics for transplant morbidities would enable personalized management in pre- and post-transplant care.

Post-transplant recurrence of focal segmental glomerular sclerosis: consensus statements

Focal segmental glomerular sclerosis (FSGS) is 1 of the primary causes of nephrotic syndrome in both pediatric and adult patients, which can lead to end-stage kidney disease. Recurrence of FSGS after kidney transplantation significantly increases allograft loss, leading to morbidity and mortality. Currently, there are no consensus guidelines for identifying those patients who are at risk for recurrence or for the management of recurrent FSGS. Our work group performed a literature search on PubMed/Medline, Embase, and Cochrane, and recommendations were proposed and graded for strength of evidence. Of the 614 initially identified studies, 221 were found suitable to formulate consensus guidelines for recurrent FSGS. These guidelines focus on the definition, epidemiology, risk factors, pathogenesis, and management of recurrent FSGS. We conclude that additional studies are required to strengthen the recommendations proposed in this review.

Focal segmental glomerulosclerosis: Risk for recurrence and interventions to optimize outcomes following recurrence

BACKGROUND

FSGS is a common indication for kidney transplant with a high-risk of posttransplant recurrence.

METHODS

In this review, we summarize current knowledge about FSGS recurrence after kidney transplantation, including epidemiology, pretransplant planning, posttransplant management, and investigational treatments.

RESULTS

FSGS recurs in 14%-60% of first transplants, likely associated with a circulating permeability factor. Pretransplant counseling regarding recurrence is critical, and patients with FSGS should undergo pretransplant genetic screening. Rapid progression to ESKD, initial steroid responsiveness, younger age at diagnosis, race/ethnicity, and mesangial hypercellularity or minimal change histology on native biopsy may be associated with recurrence. Living donation is not contraindicated but does not result in improved graft survival relative to deceased donation. Pretransplant nephrectomy may be performed for a variety of reasons, but does not decrease recurrence. Pretransplant therapy with rituximab and/or PE is understudied but not clearly effective at preventing recurrence. Patients with FSGS typically present early with rapid-onset severe proteinuria. Diagnosis can be confirmed by biopsy showing foot process effacement; typical FSGS lesions are not seen on light microscopy in the early stages. There is no established effective treatment for recurrent FSGS, but renin-angiotensin-aldosterone system inhibition and extracorporeal therapies, including PE and IA, are most commonly used. Adjunct or alternative therapies may include rituximab, lipopheresis, and cyclosporine.

Overview of pediatric kidney transplantation

Kidney transplantation is the treatment of choice for pediatric patients with end-stage kidney disease. Unlike adult recipients undergoing transplantation, special considerations must be taken when transplanting children based on the underlying etiology of kidney disease, previous surgical procedures, anatomical limitations and necessary technical adjustments. Additionally, the choice of donor must be measured to ensure optimal graft survival given a longer post-transplant life expectancy. Those topics as well as frequently encountered postoperative complications are also discussed in this publication.

Genetic Spectrum of Nephrotic Syndrome: Impact of Podocytopathy in Adult Life

A substantial number of patients with focal segmental glomerulosclerosis (FSGS) have a pathogenic genetic mutation in a podocyte protein as the cause of their disease. The mutations can affect a wide range of cell functions including the actin cytoskeleton, cell adhesion and motility, mitochondrial function, and nuclear pore proteins. The likelihood of a genetic cause declines with age, from approximately 30% in children and adolescents to 10% in adulthood, and the specific proteins involved and the pattern of inheritance differ in the 2 age groups. The presence of a genetic cause for FSGS can have important clinical ramifications including the need for a diagnostic kidney biopsy, medical management, and the risk of recurrent disease after kidney transplantation. This review summarizes the spectrum of genetic causes of nephrotic syndrome, primarily FSGS, in adults with a focus on diagnosis, presentation, and management.

Evaluation of Genetic Kidney Diseases in Living Donor Kidney Transplantation: Towards Precision Genomic Medicine in Donor Risk Assessment

Purpose of Review

To provide a comprehensive update on the role of genetic testing for the evaluation of kidney transplant recipient and living donor candidates.

Recent Findings

The evaluation of candidates for living donor transplantation and their potential donors occurs within an ever-changing landscape impacted by new evidence and risk assessment techniques. Criteria that were once considered contraindications to living kidney donation are now viewed as standard of care, while new tools identify novel risk markers that were unrecognized in past decades. Recent work suggests that nearly 10% of a cohort of patients with chronic/end-stage kidney disease had an identifiable genetic etiology, many whose original cause of renal disease was either unknown or misdiagnosed. Some also had an incidentally found genetic variant, unrelated to their nephropathy, but medically actionable. These patterns illustrate the substantial potential for genetic testing to better guide the selection of living donors and recipients, but guidance on the proper application and interpretation of novel technologies is in its infancy. In this review, we examine the utility of genetic testing in various kidney conditions, and discuss risks and unresolved challenges. Suggested algorithms in the context of related and unrelated donation are offered.

Summary

Genetic testing is a rapidly evolving strategy for the evaluation of candidates for living donor transplantation and their potential donors that has potential to improve risk assessment and optimize the safety of donation.

OUP accepted manuscript

Podocytopathies are glomerular disorders in which podocyte injury drives proteinuria and progressive kidney disease. They encompass a broad spectrum of aetiologies, resulting in pathological pictures of minimal-changes, focal segmental glomerulosclerosis, diffuse mesangial sclerosis or collapsing glomerulopathy. Despite improvement in classifying podocytopathies as a distinct group of disorders, the histological definition fails to capture the relevant biological heterogeneity underlying each case, manifesting as extensive variability in disease progression and response to therapies. Increasing evidence suggests that podocytopathies can result from a single causative factor or a combination of multiple genetic and/or environmental risk factors with different relative contributions, identifying complex physiopathological mechanisms. Consequently, the diagnosis can still be challenging. In recent years, significant advances in genetic, microscopy and biological techniques revolutionized our understanding of the molecular mechanisms underlying podocytopathies, pushing nephrologists to integrate innovative information with more conventional data obtained from kidney biopsy in the diagnostic workflow. In this review, we will summarize current approaches in the diagnosis of podocytopathies, focusing on strategies aimed at elucidating the aetiology underlying the histological picture. We will provide several examples of an integrative view of traditional concepts and new data in patients with suspected podocytopathies, along with a perspective on how a reclassification could help to improve not only diagnostic pathways and therapeutic strategies, but also the management of disease recurrence after kidney transplantation. In the future, the advantages of precision medicine will probably allow diagnostic trajectories to be increasingly focused, maximizing therapeutic results and long-term prognosis.

A critical re-analysis of cases of post-transplantation recurrence in genetic nephrotic syndrome

BACKGROUND

Genetic defects in podocyte proteins account for up to 30% of steroid-resistant nephrotic syndrome (SRNS) in the paediatric population. Most children with genetic SRNS are resistant to immunosuppression and at high risk of progression to stage 5 chronic kidney disease. Kidney transplantation is often the treatment of choice. The possibility of post-transplantation disease recurrence in genetic SRNS remains controversial, and poses fundamental questions about disease biology.

METHODS

We critically evaluated the published cases of post-transplantation recurrence in genetic patients, particularly testing 'mutations' against the most recent population variant databases, in order to clarify the diagnoses, and compare the clinical courses and responses to therapy.

RESULTS

Biallelic pathogenic variants in NPHS1 leading to a complete absence of nephrin were the most commonly reported and best understood instance of nephrotic syndrome occurring post-transplantation. This is an immune-mediated process driven by antibody production against the novel nephrin protein in the allograft. We also identified a number of plausible reported cases of post-transplantation recurrence involving pathogenic variants in NPHS2 (8 patients, biallelic), one in WT1 (monoallelic) and one in NUP93 (biallelic). However, the mechanism for recurrence in these cases remains unclear. Other instances of recurrence in genetic disease were difficult to interpret due to differing clinical criteria, inclusion of patients without true pathogenic variants or the influence of other factors on renal outcome.

CONCLUSIONS

Overall, post-transplantation recurrence remains very rare in patients with genetic SRNS. It appears to occur later after transplantation than in other patients and usually responds well to plasmapheresis with a good renal outcome.

Chronic Kidney Allograft Disease: New Concepts and Opportunities

Chronic kidney disease (CKD) is increasing in most countries and kidney transplantation is the best option for those patients requiring renal replacement therapy. Therefore, there is a significant number of patients living with a functioning kidney allograft. However, progressive kidney allograft functional deterioration remains unchanged despite of major advances in the field. After the first post-transplant year, it has been estimated that this chronic allograft damage may cause a 5% graft loss per year. Most studies focused on mechanisms of kidney graft damage, especially on ischemia-reperfusion injury, alloimmunity, nephrotoxicity, infection and disease recurrence. Thus, therapeutic interventions focus on those modifiable factors associated with chronic kidney allograft disease (CKaD). There are strategies to reduce ischemia-reperfusion injury, to improve the immunologic risk stratification and monitoring, to reduce calcineurin-inhibitor exposure and to identify recurrence of primary renal disease early. On the other hand, control of risk factors for chronic disease progression are particularly relevant as kidney transplantation is inherently associated with renal mass reduction. However, despite progress in pathophysiology and interventions, clinical advances in terms of long-term kidney allograft survival have been subtle. New approaches are needed and probably a holistic view can help. Chronic kidney allograft deterioration is probably the consequence of damage from various etiologies but can be attenuated by kidney repair mechanisms. Thus, besides immunological and other mechanisms of damage, the intrinsic repair kidney graft capacity should be considered to generate new hypothesis and potential therapeutic targets. In this review, the critical risk factors that define CKaD will be discussed but also how the renal mechanisms of regeneration could contribute to a change chronic kidney allograft disease paradigm.

KDIGO Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation

The 2020 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation is intended to assist health care professionals worldwide who evaluate and manage potential candidates for deceased or living donor kidney transplantation. This guideline addresses general candidacy issues such as access to transplantation, patient demographic and health status factors, and immunological and psychosocial assessment. The roles of various risk factors and comorbid conditions governing an individual's suitability for transplantation such as adherence, tobacco use, diabetes, obesity, perioperative issues, causes of kidney failure, infections, malignancy, pulmonary disease, cardiac and peripheral arterial disease, neurologic disease, gastrointestinal and liver disease, hematologic disease, and bone and mineral disorder are also addressed. This guideline provides recommendations for evaluation of individual aspects of a candidate's profile such that each risk factor and comorbidity are considered separately. The goal is to assist the clinical team to assimilate all data relevant to an individual, consider this within their local health context, and make an overall judgment on candidacy for transplantation. The guideline development process followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. Guideline recommendations are primarily based on systematic reviews of relevant studies and our assessment of the quality of that evidence, and the strengths of recommendations are provided. Limitations of the evidence are discussed with differences from previous guidelines noted and suggestions for future research are also provided.

Management of congenital nephrotic syndrome: consensus recommendations of the ERKNet-ESPN Working Group

Congenital nephrotic syndrome (CNS) is a heterogeneous group of disorders characterized by nephrotic-range proteinuria, hypoalbuminaemia and oedema, which manifest in utero or during the first 3 months of life. The main cause of CNS is genetic defects in podocytes; however, it can also be caused, in rare cases, by congenital infections or maternal allo-immune disease. Management of CNS is very challenging because patients are prone to severe complications, such as haemodynamic compromise, infections, thromboses, impaired growth and kidney failure. In this consensus statement, experts from the European Reference Network for Kidney Diseases (ERKNet) and the European Society for Paediatric Nephrology (ESPN) summarize the current evidence and present recommendations for the management of CNS, including the use of renin-angiotensin system inhibitors, diuretics, anticoagulation and infection prophylaxis. Therapeutic management should be adapted to the clinical severity of the condition with the aim of maintaining intravascular euvolaemia and adequate nutrition, while preventing complications and preserving central and peripheral vessels. We do not recommend performing routine early nephrectomies but suggest that they are considered in patients with severe complications despite optimal conservative treatment, and before transplantation in patients with persisting nephrotic syndrome and/or a WT1-dominant pathogenic variant.

Case Report: The Monogenic Familial Steroid-Resistant Nephrotic Syndrome Caused by a Novel Missense Mutation of NPHS2 Gene A593C in a Chinese Family

Background: Pathogenic variants in the NPHS2 gene encoding podocin in kidney podocytes are associated with autosomal recessive steroid-resistant nephrotic syndrome (SRNS) by disrupting podocyte function and the integrity of the glomerular filtration barrier. The outcome is generally poor by progressing into end-stage kidney disease (ESKD). With the help of gene diagnostics, we can further understand the role of podocin of podocytes in the development and progression of SRNS. However, the pathological mutation of NPHS2 and clinical relevance remain further elusive. Case Presentation: Two siblings, a 15-year-old girl and her 10-year-old younger brother from a consanguineous Chinese family, presented with nephrotic syndrome. Both of them developed progressive proteinuria starting from the 5-year-old of age. The renal pathological lesions for them revealed focal segmental glomerulosclerosis (FSGS). There was no response to the glucocorticoid, calcineurin inhibitors, and rituximab treatment. The female affected patient received the hemodialysis treatment due to ESKD in June 2020; the male patient was still in follow-up presenting with SRNS. The mutational screening of the two patients and their parents using Trio whole-exome sequencing showed the NPHS2 gene de novo missense mutation in exon 5 (A593C), for which the two siblings were homozygous and their parents confirmed heterozygous asymptomatic carriers. No other SRNS-related gene variants with the SRNS were determined. Conclusion: Pathological gene variants screening in children clinically suspected with SRNS might be helpful in the diagnosis as well as appropriate decisions on treatment strategies and prediction of prognosis.

Genetic studies of focal segmental glomerulosclerosis: a waste of scientific time?

Many genetic causes of focal segmental glomerulosclerosis (FSGS) have been described. A paradox is that the science in the molecular biology, which generally appears of high quality, is not mirrored by a similarly critical analysis of the renal pathology. FSGS has been applied to such a wide range of conditions that it can reasonably be said to have no useful meaning. Attempts to refine the term have been largely ignored. Study of 252 papers on genetic causes of FSGS found various clinical features. Many papers took the reported diagnosis without question. Few papers reported a pathological review, almost half reported FSGS and up to six other conditions caused by any particular gene, some reported FSGS with recognisable glomerular disorders, over 80% did not apply the Columbia classification, and in nearly all with photomicrographs, the images were not useful for refinement of FSGS. Some workers commented on a lack of genotype-phenotype correlation. One reason is a disregard of the principle that scientific investigation requires an unambiguous definition of the condition studied, to allow others to replicate or refute the findings. Genetic studies of FSGS should use a similarly rigorous approach to renal pathology to that used in molecular biology.

Post-transplant recurrence of steroid resistant nephrotic syndrome in children: the Italian experience

Background

Steroid resistant nephrotic syndrome (SRNS) is a frequent cause of end stage renal disease in children and post-transplant disease recurrence is a major cause of graft loss.

Methods

We identified all children with SRNS who underwent renal transplantation in Italy, between 2005 and 2017. Data were retrospectively collected for the presence of a causative gene mutation, sex, histology, duration of pre-transplant dialysis, age at onset and transplant, HLA matching, recurrence, therapy for recurrence, and graft survival.

Results

101 patients underwent a first and 22 a second renal transplant. After a median follow-up of 58.5 months, the disease recurred on the first renal transplant in 53.3% of patients with a non-genetic and none with a genetic SRNS. Age at transplant > 9 years and the presence of at least one HLA-AB match were independent risk factors for recurrence. Duration of dialysis was longer in children with relapse, but did not reach statistical significance. Overall, 24% of patients lost the first graft, with recurrence representing the commonest cause. Among 22 patients who underwent a second transplant, 5 suffered of SRNS recurrence. SRNS relapsed in 5/9 (55%) patients with disease recurrence in their first transplant and 2 of them lost the second graft.

Conclusions

Absence of a causative mutation represents the major risk factor for post-transplant recurrence in children with SRNS, while transplant can be curative in genetic SRNS. A prolonged time spent on dialysis before transplantation has no protective effect on the risk of relapse and should not be encouraged. Retransplantation represents a second chance after graft loss for recurrence.

Recurrent and de novo Glomerulonephritis After Kidney Transplantation

The prevalence, pathogenesis, predictors, and natural course of patients with recurrent glomerulonephritis (GN) occurring after kidney transplantation remains incompletely understood, including whether there are differences in the outcomes and advances in the treatment options of specific GN subtypes, including those with de novo GN. Consequently, the treatment options and approaches to recurrent disease are largely extrapolated from the general population, with responses to these treatments in those with recurrent or de novo GN post-transplantation poorly described. Given a greater understanding of the pathogenesis of GN and the development of novel treatment options, it is conceivable that these advances will result in an improved structure in the future management of patients with recurrent or de novo GN. This review focuses on the incidence, genetics, characteristics, clinical course, and risk of allograft failure of patients with recurrent or de novo GN after kidney transplantation, ascertaining potential disparities between “high risk” disease subtypes of IgA nephropathy, idiopathic membranous glomerulonephritis, focal segmental glomerulosclerosis, and membranoproliferative glomerulonephritis. We will examine in detail the management of patients with high risk GN, including the pre-transplant assessment, post-transplant monitoring, and the available treatment options for disease recurrence. Given the relative paucity of data of patients with recurrent and de novo GN after kidney transplantation, a global effort in collecting comprehensive in-depth data of patients with recurrent and de novo GN as well as novel trial design to test the efficacy of specific treatment strategy in large scale multicenter randomized controlled trials are essential to address the knowledge deficiency in this disease.

European Society of Pediatric Nephrology survey on current practice regarding recurrent focal segmental glomerulosclerosis after pediatric kidney transplantation

INTRODUCTION

Primary FSGS is an important cause of ESRD in children. FSGS recurrence after kidney transplantation is associated with early graft loss. No guidelines for treatment of FSGS recurrence exist. We conducted a survey to gain insight into variation of treatment between centers.

METHODS

A survey was sent to all members of the ESPN on behalf of the "Renal Transplantation" and "Idiopathic Nephrotic Syndrome" working groups.

RESULTS

Fifty-nine nephrologists from 31 countries responded, reporting 807 FSGS patients, with 241 (30%) FSGS recurrences after transplantation. Recurrence varied from 0% to 100% between respondents. Native nephrectomy before or during transplantation was performed, respectively, always (37%), never (39%), or on clinical indication (17%). Half of the respondents started preventive treatment before transplantation, using PF (n = 10); R (n = 4); PF or IA, plus R (n = 9); cyclosporine (n = 2); or unknown (n = 4). Immunosuppressive therapy for patients without known mutations consisted of a combination of steroids, tacrolimus/cyclosporine, and MMF, with or without IL-2R-blockade in, respectively, 61% and 86% of the respondents. Sixty-three percent applied a similar regimen to patients with known mutations. FSGS recurrence was treated with PF or IA, plus R by 66% of respondents; 54% observed no response. Complete remission in >50% of patients was reported by 41% of the respondents.

DISCUSSION

FSGS recurrence after transplantation is common, but varies greatly between centers. We found great variability in preventive and therapeutic treatment regimens. Future research should focus on predisposing factors, including biopsy findings and genetic mutations, and standardized treatment.

The mutation-dependent pathogenicity of NPHS2 p.R229Q: A guide for clinical assessment

NPHS2, encoding podocin, is the major gene implicated in steroid-resistant nephrotic syndrome. Its c.686G>A, p.R229Q variant is the first human variant with a mutation-dependent pathogenicity; it is only pathogenic when trans-associated to specific mutations. Secondary to its high allele frequency in the European, South Asian, African, and Latino populations, its benign trans-associations can be accidentally identified in affected patients. Distinguishing pathogenic and benign p.R229Q associations can be challenging. In this paper, we present the currently known pathogenic and benign associations, and show that a rare p.R229Q association can be considered pathogenic if the variant in trans meets the following criteria; it affects the 270-351 residues and alters but does not disrupt the oligomerization, its p.R229Q association is found in a family with slowly progressing focal segmental glomerulosclerosis, but is expected to be rare in the general population (<1:10⁶ ). We show that >15% of the p.R229Q associations identified so far in patients are benign.

Deriving and understanding the risk of post-transplant recurrence of nephrotic syndrome in the light of current molecular and genetic advances

After renal transplantation, recurrence of the original disease is the second most common cause of graft loss, after rejection. The most dramatic manifestation of this phenomenon is in patients with nephrotic syndrome (NS). NS is a descriptive term describing a clinical picture centred on proteinuria arising from damage to the glomerular filtration barrier (GFB). There are many different drivers of that damage, ranging from immune dysregulation to genetic disorders and chronic disease/infections. The main categories in childhood are "idiopathic" (presumed immune mediated) and genetic NS, with further stratification of the idiopathic group according to steroid responses. A significant proportion of patients with NS progress to established renal failure, requiring transplantation, and one of the most difficult clinical scenarios faced by nephrologists is the recurrence of the original disease in up to 50% of patients, usually rapidly post-transplant. This is thought to be the archetypal "circulating factor" disease, in which as yet unknown circulating plasma "factor(s)" in the recipient target the donor kidney. The ability to predict in advance which patients will suffer recurrence would enhance our ability to counsel patients and families, and potentially identify those patients before transplant for tailored immunosuppressive preparation. Until very recently, stratification based on clinical categorisations has been poor in being able to predict those patients in whom disease will recur, and laboratory biomarkers are yet to be adequately refined. However, by mapping our growing understanding of disease mechanisms to clinical phenotypes, and with greatly improved genetic diagnostics, we have made progress in being able to stratify patients more specifically, and allow better predictive algorithms to be developed. Using our knowledge of podocyte biology, circulating factor-induced specific biomarkers are also being tested. This review is aimed at outlining those advances, and suggesting how we can move further forward in both clinical and biological markers of disease type.

Recurrence of primary glomerulonephritis: Review of the current evidence

In view of the availability of new immunosuppression strategies, the recurrence of allograft glomerulonephritis (GN) are reported to be increasing with time post transplantation. Recent advances in understanding the pathogenesis of the GN recurrent disease provided a better chance to develop new strategies to deal with the GN recurrence. Recurrent GN diseases manifest with a variable course, stubborn behavior, and poor response to therapy. Some types of GN lead to rapid decline of kidney function resulting in a frustrating return to maintenance dialysis. This subgroup of aggressive diseases actually requires intensive efforts to ascertain their pathogenesis so that strategy could be implemented for better allograft survival. Epidemiology of native glomerulonephritis as the cause of end-stage renal failure and subsequent recurrence of individual glomerulonephritis after renal transplantation was evaluated using data from various registries, and pathogenesis of individual glomerulonephritis is discussed. The following review is aimed to define current protocols of the recurrent primary glomerulonephritis therapy.

Recurrent Nephrotic Syndrome After Renal Transplant in Children

OBJECTIVES

Recurrent disease occurs in around 30% of children transplanted for steroid-resistant nephrotic syndrome. Its precipitating risk factors have rarely been studied in the Middle East. The aim of our study was to determine what characterizes posttransplant recurrence of nephrotic syndrome in Syrian children.

MATERIALS AND METHODS

We performed a retrospective analysis of 12 nephrotic children who received 1 renal allograft at the Kidney Hospital in Damascus from 2002 to 2013.

RESULTS

Native kidney biopsy results showed focal segmental glomerulosclerosis in 9 of 10 patients. Four patients had 1 or more sibling affected with nephrotic syndrome, and the remaining patients were labeled as having sporadic disease. Genetic screening for NPHS2, NPHS1, and Wilms tumor gene (WT1) mutations were done for 6 patients, and 1 novel homozygous NPHS2 mutation was identified in 1 patient. All patients received transplants from living donors. Four patients had recurrence of initial disease after transplant (overall recurrence rate of 33%). However, 1 patient showed complete and spontaneous remission 20 months after transplant; As expected, the patient with NPSH2 mutation had no recurrence. Patients with sporadic disease showed risk of recurrence 5 times higher than patients with familial disease (P = .24). Interestingly, all recurrent cases had received a kidney from a related donor and were initially classified as having sporadic disease. Although not statistically significant, the risk of recurrence from related donor grafts was 6.75 times higher than from unrelated donors (P = .16). To the best of our knowledge, this observation, the first of its kind, has never been investigated or pointed out in the literature.

CONCLUSIONS

Further research is needed to confidently determine whether living related donor grafts are associated with increased incidence of recurrence of nephrotic syndrome.

Recent advances in our understanding of recurrent primary glomerulonephritis after kidney transplantation

Recurrent glomerulonephritis (GN) is an important cause of kidney allograft failure, particularly in younger recipients. Approximately 15% of death-censored graft failures are due to recurrent GN, but this incidence is likely an underestimation of the magnitude of the problem. Overall, 18% to 22% of kidney allografts are lost due to GN, either recurrent or presumed de novo. The impact of recurrent GN on allograft survival was recognized from the earliest times in kidney transplantation. However, progress in this area has been slow, and our understanding of GN recurrence remains limited, in large part due to incomplete understanding of the pathogenesis of these diseases. This review focuses on recent advances in our general understanding of the pathophysiology of primary GN, the risk of recurrence in the allograft, and the consequences for kidney graft survival. We focus specifically on the most common forms of primary GN, including focal segmental glomerulosclerosis, membranous nephropathy, membranoproliferative glomerulonephritis, and IgA nephropathy. New understanding of the pathogenesis of these diseases has had direct clinical implications for transplantation, allowing better identification of candidates at high risk of recurrence and earlier diagnoses, and it is expected to lead to significance improvements in the therapy and perhaps even prevention of GN recurrence. More than ever, it is essential to fully characterize GN before transplantation as this information will direct our management posttransplantation. Further, the relative rarity of recurrent GN dictates the need for multicenter studies in order to evaluate, test, and validate recent advances and therapies.

Soluble Urokinase Receptors in Focal Segmental Glomerulosclerosis: A Review on the Scientific Point of View

Focal segmental glomerulosclerosis (FSGS) is one of the primary glomerular disorders in both children and adults which can progress to end-stage renal failure. Although there are genetic and secondary causes, circulating factors have also been regarded as an important factor in the pathogenesis of FSGS, because about 40% of the patients with FSGS have recurrence after renal transplantation. Soluble urokinase-type plasminogen activator receptor (suPAR) is a soluble form of uPAR, which is a membrane-bound protein linked to GPI in various immunologically active cells, including podocytes. It has recently been suggested as a potential circulating factor in FSGS by in vitro podocyte experiments, in vivo mice models, and human studies. However, there have also been controversies on this issue, because subsequent studies showed conflicting results. suPAR levels were also increased in patients with other glomerular diseases and were inversely correlated with estimated glomerular filtration rate. Nevertheless, there has been no balanced review on this issue. In this review, we compare the conflicting data on the involvement of suPAR in the pathogenesis of FSGS and shed light on interpretation by taking into account many points and the potential variables and confounders influencing serum suPAR levels.

Post-Transplant Recurrence of Focal Segmental Glomerulosclerosis in a Child With Heterozygous Mutations in NPHS1 and NPHS2

Renal transplantation is the optimal renal replacement therapy (RRT) in children, but some primary diseases can recur after transplantation, and recurrence accounts for a significant proportion of graft losses, being second only to acute rejection. The risk of disease recurrence is highest among patients with idiopathic focal segmental glomerulosclerosis (FSGS), presumably due to a circulating permeability factor. Less is clear about the genetic forms of FSGS, where the data regarding the frequency of recurrence are rather conflicting. We present a 12-year-old girl with rapidly progressive FSGS and end-stage renal disease in her native kidneys associated with heterozygous mutations in NPHS1 and in NPHS2, suffering from early post-transplant recurrence. On the basis of reviewed literature, and until further and more conclusive evidence considering pathogenicity is provided, we propose that FSGS patients with heterozygous mutations in NPHS1 or NPHS2 should be considered as having idiopathic FSGS, and post-transplant recurrence should be anticipated.

FSGS Recurrence in Adults after Renal Transplantation

Recurrence of focal segmental glomerulosclerosis (FSGS) in the allograft occurs in 30–50% of patients, and it is associated with poor renal allograft survival. Major risk factors for recurrence are younger age at diagnosis, rapid progression to end-stage renal disease, white race, and the loss of previous allografts due to recurrence. Recent data support the hypothesis that circulating permeability factors play a crucial role in podocyte injury and progression of FSGS. Due to lack of controlled trials, the management of recurrent FSGS is inconsistent and highly empirical. Prophylactic and perioperative treatment with plasmapheresis and high-dose (intravenous) cyclosporine represent the main cornerstones of immunosuppressive therapy. In recent years, therapy with rituximab has shown promising results. Despite evidence of activation of the renin-angiotensin system (RAS) in recurrent FSGS and its association with progression, only limited data exist on the renoprotective role of RAS blockade in this setting. Further well designed studies are needed on pathogenesis risk factors and therapeutical options in FSGS and its recurrence after transplantation.

Recurrent focal segmental glomerulosclerosis after kidney transplantation

Focal segmental glomerulosclerosis (FSGS) is an important cause of glomerular disease in children and adolescents and nearly 50 % of affected patients will progress to end-stage kidney disease over a 5 to 10-year period. Unfortunately, there is no established treatment for disease in the native kidney. Moreover, up to 55 % of patients develop recurrent disease after receiving a kidney transplant, with a substantially higher risk in patients who have already experienced recurrent disease in a prior transplant. A number of clinical and laboratory factors have been identified as risk factors for this complication. In addition, new investigations into podocyte biology and circulating permeability factors have shed light on the cause of recurrent the disease. While a number of novel therapeutic agents have been applied in the management of this problem, there still is no proven treatment. In this review, we summarize recent advances in the epidemiology, pathophysiology, and treatment of recurrent FSGS in pediatric patients who have received a kidney transplant.

The amino acid mutations of the podocin in proteinuria: a meta-analysis

While many previous studies have reported an association between the single-nucleotide polymorphisms (SNPs) of the podocin and proteinuria occurred, a conclusive relationship has not been defined in every oligoallelic state of amino acid (AA) mutations in podocin. In this study, we performed a meta-analysis of the published data to investigate the impact of the oligoallelic AA mutations of the podocin on proteinuria; a total 16 AA mutations were investigated for oligoallelic pathogenicity. Despite significant heterogeneity within some of the comparisons, the results revealed significantly higher risks of proteinuria in early-onset (onset age <16) individuals for five mutations (P118L, R138Q, R168H, V180M, and V260E), and in all onset ages individuals for five mutations (R138Q, G140X, R229Q, V260E, and V290M) compared to non-variant individuals. We also tested the steroid response in individuals with R229Q and E237Q. No statistically significant differences in the two mutations carrier rate were observed between steroid resistance patients and controls. No AA mutation was selected for meta-analysis on the recurrence of proteinuria after renal transplantation as lack of control data. In conclusion, our meta-analysis tested the pathogenicity of the oligoallelic AA mutations in podocin and suggested the potential causative mutations, and the alleles showing an association with protein susceptibility. The sensitivity and specificity of each causative mutation are pending further testing.

Renal transplantation in children with nephrotic syndrome in the first year of life

OBJECTIVE

The aim of this work was to analyze the evolution of the 1st renal transplantation in children with nephrotic syndrome in the 1st year of life (NSFL).

METHODS

In this retrospective study of 15 patients (8 women and 7 men) with NSFL receiving transplants from 1989 to 2013, 9 had NS of Finnish type, 4 diffuse mesangial sclerosis, 1 minimal changes, and 1 collapsing glomerulopathy. We analyzed the clinical and analytic situation at 4 time points: before dialysis, before transplantation, 3 months after transplantation, and long-term evolution.

RESULTS

Mean follow-up was 72.8 months (range, 1 month to 16.9 years); mean age at diagnosis was 2.21 months (range, 0-8.2 months); mean age at onset of replacement therapy was 22.9 ± 16.4 months (range, 3.8-55.4 months); and mean time on dialysis was 14.9 months (range, 2-44 months). Age at transplantation was 3.1 years (range, 1.8 to 7.7 years), with 6 living-donor transplantations (LDTs) and 9 cadaveric (CDTs). Ten patients required nephrectomy before transplantation (9 bilateral) to control proteinuria after 3.1 ± 3.8 months on dialysis, 1 during transplantation, and 3 after transplantation (2 persistent proteinuria, 1 hypertension). Mean time on dialysis for LDTs was 5.4 ± 2.7 months versus 13.2 ± 6.9 months for CDTs (P < .005). Mean age of cadaveric donors was 6.2 ± 2.4 years and that of living donors 35.5 ± 7.9 years. As complications, there was 1 bleeding from venous anastomosis and 1 urinary leakage after surgery. After 6 ± 5.2 years of evolution, actuarial survival at both 1 and 7 years was 92.9%. One graft was lost owing to acute rejection 1 month after transplantation and 2 others owing to chronic rejection >9 years after transplantation. None had disease recurrence.

CONCLUSIONS

Short-term complications did not differ from the rest of population if transplantation occurred with standard albumin levels, for which most required pre-transplantation nephrectomy because dialysis failed to reduce proteinuria.

Focal segmental glomerulosclerosis recurrence in the renal allograft

Focal segmental glomerulosclerosis (FSGS) represents a common histologic pattern of glomerular injury associated with a multitude of disease mechanisms. The etiology of FSGS is often classified into primary (idiopathic) and secondary forms in response to genetic abnormalities, infections, toxins, and systemic disorders that lead to adaptive changes, glomerular hyperfiltration, and proteinuria. Our understanding of the pathogenic mechanisms responsible for FSGS was substantially enhanced in recent years because of major advances in the cell biology of the podocyte and parietal epithelial cell. Recurrence of FSGS occurs mainly in its primary form and is only rarely described in secondary forms. The re-enactment of pathologic mechanisms of FSGS as recurrent disease after kidney transplantation represents a biologic experiment that can provide unique insight. Nonetheless, recurrent FSGS remains a notable clinical problem that correlates with poorer renal allograft outcomes. This is the focus of this particular review, concentrating on the most recent developments.

Steroid-resistant nephrotic syndrome with mutations in NPHS2 (podocin): report from a three-generation family

Genetic causes of steroid-resistant nephrotic syndrome are being increasingly recognized. Mutations in NPHS2, which encodes the glomerular protein podocin, account for up to 17% of sporadic and 40% of familial cases, where they display an autosomal-recessive pattern of inheritance. This report describes a non-consanguineous family with three generations of individuals who are either compound heterozygotes for mutations in NPHS2 or who have inherited a mutation and a non-neutral polymorphism (R229Q). As well as providing an aetiological explanation, identifying pathogenic mutations and considering genotype-phenotype correlations can provide prognostic information and lead to changes in genetic counselling and management.

Congenital nephrotic syndrome and recurrence of proteinuria after renal transplantation

Renal transplantation (RTx) is the only curative treatment for most cases of congenital and infantile nephrotic syndrome (NS) caused by genetic defects in glomerular podocyte proteins. The outcome of RTx in these children is usually excellent, with no recurrence of nephrotic syndrome. A subgroup of patients with the Finnish type of congenital nephrosis (CNF), shows, however, a clear risk for post-RTx proteinuria. Most of these patients have a homozygous truncating mutation (Fin-major mutation) in the nephrin gene (NPHS1), leading to total absence of the major podocyte protein, nephrin. After RTx, these patients develop anti-nephrin antibodies resulting in nephrotic range proteinuria. Plasma exchange combined with cyclophosphamide and anti-CD20 antibodies has proved to be successful therapy for these episodes. NS recurrence has also occurred in a few patients with mutations in the podocin gene (NPHS2). No anti-podocin antibodies have been detectable, and the pathophysiology of the recurrence remains open. While most of these episodes have resolved, the optimal therapy remains to be determined.

Hsf-1 affects podocyte markers NPHS1, NPHS2 and WT1 in a transgenic mouse model of TTRVal30Met-related amyloidosis

INTRODUCTION

Familial amyloid polyneuropathy is characterized by transthyretin (TTR) deposition in various tissues, including the kidneys. While deposition induces organ dysfunction, renal involvement in TTR-related amyloidosis could manifest from proteinuria to end-stage kidney failure. As proteinuria is considered result of glomerular filtration barrier injury we investigated whether TTR deposition affects either glomerular basement membrane (GBM) or podocytes.

MATERIALS AND METHODS

Immunohistochemistry, immunoblot and gene expression studies for nephrin, podocin and WT1 were run on renal tissue from human-TTRV30M transgenic mice hemizygous or homozygous for heat shock factor one (Hsf-1). Transmission electron microscopy was used for evaluation of podocyte foot process width (PFW) and GBM thickness in Hsf-1 hemizygous mice with or without TTRV30M or amyloid deposition.

RESULTS

Glomeruli of hsf-1 hemizygous transgenic mice showed lower nephrin and podocin protein levels but an increased podocyte number when compared to Hsf-1 homozygous transgenic mice. Nephrin, podocin and WT1 gene expression levels were unaffected by the Hsf-1 carrier status. TTRV30M deposition was associated with increased PFW and GBM thickness.

CONCLUSIONS

Under the effect of Hsf-1 hemizygosity, TTRV30M deposition has deleterious effects on GBM thickness, PFW and slit diaphragm composition, without affecting nephrin and podocin gene expression.

Genetics of steroid-resistant nephrotic syndrome: a review of mutation spectrum and suggested approach for genetic testing

Identification of genes, associated mutations and genotype-phenotype correlations in steroid-resistant nephrotic syndrome (SRNS) is being translated to clinical practice through genetic testing. This review provides an update on the genes and mutations associated with SRNS along with a suggested approach for genetic testing in patients with SRNS.

CONCLUSION

The number of indentified genes associated with SRNS is increasing along with our understanding of their impact on treatment response and risk of recurrence. A systematic approach to genetic testing in patients with SRNS might aid the physician in selecting appropriate treatment.

Glomerular disease recurrence in the renal allograft: a hurdle but not a barrier for successful kidney transplantation

Almost all forms of primary as well as secondary glomerulonephritides may recur after renal transplantation. Recurrence of the original disease is now the third most common cause of late allograft loss. Nevertheless, in most cases it is difficult to assess the true impact of primary disease recurrence in the allograft; histological recurrence with mild features does not necessarily implicate clinically severe disease. Moreover it is often difficult to distinguish recurrent from de novo disease as in membranous glomerulopathy. Because recurrence occurs late, histological lesions of recurrent glomerulonephritis may be unmasked by chronic damage from other causes such as chronic rejection. Beside the difficulties to interpret renal histology due to the variety of allograft lesions, there are no well-established options to prevent clinically severe disease recurrence nor the therapeutic approaches to the problem. The purpose of this review was mainly to underline that almost all primary and secondary glomerulonephritides represent a contraindication to transplantation. For the majority of patients with end-stage renal disease due to glomerulonephritis, transplantation still represents the treatment of choice.

Educational paper: the podocytopathies

In the recent past, hereditary podocytopathies have increasingly been recognized to be involved in the development of steroid-resistant nephrotic syndrome (SRNS). Mutations in podocyte genes substantially alter the development and structural architecture of the podocyte including its interdigitating foot processes. These constitute the basis of the slit diaphragm which is an essential part of the glomerular filtration barrier. Depending on the affected protein, the clinical course is variable with respect to onset and severity of the disease as well as treatment options. In general, hereditary podocytopathies are associated with a poorer renal outcome than the non-genetic variants. In addition, they require a different approach with respect to the applied therapeutic strategies as most patients do not respond to immunosuppressive agents. Therefore, genetic testing of podocyte genes should be considered as a routine diagnostic tool for patients with SRNS because the identification of a genetic origin has a direct implication on clinical course, renal outcome, and genetic counseling. In this educational paper, we will give an overview over the podocyte genes identified so far to be involved into the pathophysiology of hereditary podocytopathies.

A case of de novo focal segmental glomerulosclerosis occurred one and half years after kidney transplantation supposed to be caused by calcineurin inhibitor

A 64-yr-old man with end-stage kidney disease caused by hypertensive nephrosclerosis underwent living-unrelated ABO-identical kidney transplantation (KTx) at the age of 60 yr from his 60-yr-old wife. Maintenance trough concentration of cyclosporine A (CsA) was 100 ± 30 ng/mL. Five months after KTx, proteinuria gradually increased to around 1 g/d. TRBx at eight months after KTx revealed the new-onset alteration of mild arteriolosclerosis with intimal hyalinosis, which might reflect calcineurin inhibitor (CNI)-associated arteriopathy (CAA). Nearly one and half years after KTx, urinary protein excretion became nearly 2 g/d. TRBx revealed the advanced CAA and findings of focal segmental glomerulosclerosis (FSGS). Then, CNI was switched from CsA to tacrolimus (TAC). TRBx at two and half years after KTx revealed progressed arteriolar transmural thickening and striped fibrosis, which were supposed to be induced by an increase in serum TAC concentration because of acute enterocolitis. Then, TAC dose was reduced to serum trough concentration 5-8 ng/mL, but urinary protein excretion was increased up to 10 g/d. Reduction of TAC to trough concentration 2.0 ± 0.5 ng/mL reduced urinary protein excretion. Attempts to elevate TAC trough concentration within normal range (4-8 ng/mL) reproducibly induced the recurrence of an increase in sCr or urinary protein excretion. All these findings supported the etiology of graft dysfunction, and proteinuria of this case was FSGS.

[Pathogenesis and treatment of idiopathic nephrotic syndrome in adults]

Idiopathic nephrotic syndrome is the most frequent glomerular disease in children and in young adults. While genetic analyses have provided new insights into disease pathogenesis through the discovery of several podocyte genes mutated in distinct forms of inherited nephrotic syndrome, the molecular bases of minimal change nephrotic syndrome and focal and segmental glomerulosclerosis with relapses remain unclear. Although immune cell disorders, which may involve both innate and adaptive immunity, appear to play a role in the pathogenesis of steroid sensitive minimal change nephrotic syndrome, the mechanisms by which they induce podocyte dysfunction remain unresolved. It was postulated that podocyte injury results from a circulating factor secreted by abnormal T cells, but the possibility that bipolarity of the disease results from a functional disorder shared by both immune cells and the podocytes is not excluded. Minimal change nephrotic syndrome relapses are associated with an expansion of T and B cell compartments and production of growth factors as well as many cytokines. Dysfunction of T cells is supported by several findings including, inhibition of a type IV hypersensitivity reaction and unclassical T helper polarization, resulting from transcriptional interference between Th1 and Th2 transcriptional factors. A low serum level of some IgG fractions is frequently observed suggesting a defect in T-B cell cooperation, which remains to be explored. In this review, we discuss recent advances in the pathogenesis and the therapy of idiopathic nephrotic syndrome.

Genetic causes of focal segmental glomerulosclerosis: implications for clinical practice

Focal segmental glomerulosclerosis (FSGS) is a common cause of steroid-resistant nephrotic syndrome in children and adults. Although FSGS is considered a podocyte disease, the aetiology is diverse. In recent years, many inheritable genetic forms of FSGS have been described, caused by mutations in proteins that are important for podocyte function. In the present commentary, we review these genetic causes of FSGS and describe their prevalence in familial and sporadic FSGS. In routine clinical practice, the decision to perform the costly DNA analysis should be based on the assessment if the results affect the care of the individual patient with respect to the evaluation of extra-renal manifestations, treatment decisions, transplantation and genetic counselling.

Hypothyroidism in children with steroid-resistant nephrotic syndrome

BACKGROUND

Non-autoimmune hypothyroidism has been reported in children with congenital nephrotic syndrome. The hypothyroid state was attributed to massive prolonged thyroid hormone loss. However, this endocrine abnormality has not been reported in steroid-resistant nephrotic syndrome (SRNS) despite similar long-standing proteinuria.

METHOD

We describe all the patients with SRNS in our clinic's follow-up who developed non-autoimmune hypothyroidism.

RESULTS

Five children aged 3-11 years at diagnosis of SRNS and followed for 5-42 months developed hypothyroidism (depressed free thyroxin and elevated thyrotropin levels) without evidence of autoimmune thyroiditis. The diagnosis of hypothyroidism was not temporarily related to disease duration or renal function. The disease was resistant to all therapies, renal function deteriorated in all the patients within 1.5-14.5 years from diagnosis. Despite thyroxine treatment and a decline in renal function, thyroid hormone level normalized only after reaching end stage renal disease (ESRD) and hemodialysis start. Nephrotic syndrome recurrence after kidney transplantation (in three patients with focal segmental glomerulosclerosis) was not accompanied by recurrent hypothyroidism.

CONCLUSION

It is our impression that non-autoimmune hypothyroidism is a potential significant complication of SRNS, and should be actively sought for especially in cases with renal function deterioration. Hypothyroidism usually resolved when these patients reach ESRD. The incidence and pathogenesis of this condition require further study.

The factors that may predict response to rituximab therapy in recurrent focal segmental glomerulosclerosis: a systematic review

Recurrence of FSGS occurs in 30–40% of allografts. Therapies for recurrence are not well established. We retrieved all published reports depicting kidney transplant recipients with focal segmental glomerulosclerosis (FSGS) recurrence, treated with rituximab, to determine factors associated with treatment response. We found 18 reports of 39 transplant recipients who received rituximab. By univariate analysis for two outcomes (no response versus any response), fewer rituximab infusions and normal serum albumin at recurrence were associated with treatment response. For 3 outcomes (no response, partial and complete remission), male gender, fewer rituximab infusions, shorter time to rituximab treatment, and normal serum albumin were associated with remission. Multivariate analysis for both models revealed that normal serum albumin at FSGS recurrence and lower age at transplant were associated with response. Rituximab for recurrence of FSGS may be beneficial for only some patients. A younger age at transplant and normal serum albumin level at recurrence diagnosis may predict response.

Focal segmental glomerulosclerosis after renal transplantation

Focal segmental glomerulosclerosis (FSGS) is a clinicopathologic syndrome of proteinuria, usually of nephrotic range, associated with focal and segmental sclerotic glomerular lesions. Therefore, FSGS is diagnosed by clinical features and histopathological examination of renal biopsy. The natural history of the condition varies, and although it may respond to treatment, FSGS is an important disease in the etiology of end-stage renal disease (ESRD). Furthermore, after kidney transplantation, approximately 30% of patients with FSGS develop recurrent FSGS. The risk factors for recurrence of FSGS include childhood onset and age <15 yr, rapid progression of the primary FSGS to ESRD, recurrence of FSGS in a previous allograft, diffuse mesangial hypercellularity in the native kidney, collapsing FSGS, and podocin gene mutation. In addition, after kidney transplantation, de novo FSGS also develops in approximately 10-20% of allografts, associated with a complication of hyperfiltration injury, chronic transplant glomerulopathy, and calcineurin inhibitor toxicity. FSGS is considered a podocyte disease, and the pathology is characterized by segmental FSGS lesion with glomerular epithelial hypercellularity. The pathological diagnosis of FSGS is based on the 2004 Columbia classification system. In the present minireview, we discuss the pathology of recurrence and de novo FSGS after kidney transplantation.