Persistent DNA damage underlies tubular cell polyploidization and progression to chronic kidney disease in kidneys deficient in the DNA repair protein FAN1.

Defective DNA repair pathways contribute to the development of chronic kidney disease (CKD) in humans. However, the molecular mechanisms underlying DNA damage-induced CKD pathogenesis are not well understood. Here, we investigated the role of tubular cell DNA damage in the pathogenesis of CKD using mice in which the DNA repair protein Fan1 was knocked out. The phenotype of these mice is orthologous to the human DNA damage syndrome, karyomegalic interstitial nephritis (KIN). Inactivation of Fan1 in kidney proximal tubule cells sensitized the kidneys to genotoxic and obstructive injury characterized by replication stress and persistent DNA damage response activity. Accumulation of DNA damage in Fan1 tubular cells induced epithelial dedifferentiation and tubular injury. Characteristic to KIN, cells with chronic DNA damage failed to complete mitosis and underwent polyploidization. In vitro and in vivo studies showed that polyploidization was caused by the overexpression of DNA replication factors CDT1 and CDC6 in FAN1 deficient cells. Mechanistically, inhibiting DNA replication with Roscovitine reduced tubular injury, blocked the development of KIN and mitigated kidney function in these Fan1 knockout mice. Thus, our data delineate a mechanistic pathway by which persistent DNA damage in the kidney tubular cells leads to kidney injury and development of CKD. Furthermore, therapeutic modulation of cell cycle activity may provide an opportunity to mitigate the DNA damage response induced CKD progression.

A Rare Autosomal Dominant Variant in Regulator of Calcineurin Type 1 (RCAN1) Gene Confers Enhanced Calcineurin Activity and May Cause FSGS.

BACKGROUND: Podocyte dysfunction is the main pathologic mechanism driving the development of FSGS and other morphologic types of steroid-resistant nephrotic syndrome (SRNS). Despite significant progress, the genetic causes of most cases of SRNS have yet to be identified. METHODS: Whole-genome sequencing was performed on 320 individuals from 201 families with familial and sporadic NS/FSGS with no pathogenic mutations in any known NS/FSGS genes. RESULTS: Two variants in the gene encoding regulator of calcineurin type 1 (RCAN1) segregate with disease in two families with autosomal dominant FSGS/SRNS. In vitro, loss of RCAN1 reduced human podocyte viability due to increased calcineurin activity. Cells expressing mutant RCAN1 displayed increased calcineurin activity and NFAT activation that resulted in increased susceptibility to apoptosis compared with wild-type RCAN1. Treatment with GSK-3 inhibitors ameliorated this elevated calcineurin activity, suggesting the mutation alters the balance of RCAN1 regulation by GSK-3ß, resulting in dysregulated calcineurin activity and apoptosis. CONCLUSIONS: These data suggest mutations in RCAN1 can cause autosomal dominant FSGS. Despite the widespread use of calcineurin inhibitors in the treatment of NS, genetic mutations in a direct regulator of calcineurin have not been implicated in the etiology of NS/FSGS before this report. The findings highlight the therapeutic potential of targeting RCAN1 regulatory molecules, such as GSK-3ß, in the treatment of FSGS.

Coding practice in national and regional kidney biopsy registries.

BACKGROUND: Kidney biopsy registries all over the world benefit research, teaching and health policy. Comparison, aggregation and exchange of data is however greatly dependent on how registration and coding of kidney biopsy diagnoses are performed. This paper gives an overview over kidney biopsy registries, explores how these registries code kidney disease and identifies needs for improvement of coding practice. METHODS: A literature search was undertaken to identify biopsy registries for medical kidney diseases. These data were supplemented with information from personal contacts and from registry websites. A questionnaire was sent to all identified registries, investigating age of registries, scope, method of coding, possible mapping to international terminologies as well as self-reported problems and suggestions for improvement. RESULTS: Sixteen regional or national kidney biopsy registries were identified, of which 11 were older than 10 years. Most registries were located either in Europe (10/16) or in Asia (4/16). Registries most often use a proprietary coding system (12/16). Only a few of these coding systems were mapped to SNOMED CT (1), older SNOMED versions (2) or ERA-EDTA PRD (3). Lack of maintenance and updates of the coding system was the most commonly reported problem. CONCLUSIONS: There were large gaps in the global coverage of kidney biopsy registries. Limited use of international coding systems among existing registries hampers interoperability and exchange of data. The study underlines that the use of a common and uniform coding system is necessary to fully realize the potential of kidney biopsy registries.

Utility of Genomic Testing after Renal Biopsy.

BACKGROUND: Renal biopsy is the mainstay of renal pathological diagnosis. Despite sophisticated diagnostic techniques, it is not always possible to make a precise pathological diagnosis. Our aim was to identify a genetic cause of disease in patients who had undergone renal biopsy and determine if genetic testing altered diagnosis or treatment. METHODS: Patients with suspected familial kidney disease underwent a variety of next-generation sequencing (NGS) strategies. The subset of these patients who had also undergone native kidney biopsy was identified. Histological specimens were reviewed by a consultant pathologist, and genetic and pathological diagnoses were compared. RESULTS: Seventy-five patients in 47 families underwent genetic sequencing and renal biopsy. Patients were grouped into 5 diagnostic categories based on pathological diagnosis: tubulointerstitial kidney disease (TIKD; n = 18); glomerulonephritis (GN; n = 15); focal segmental glomerulosclerosis and Alport Syndrome (n = 11); thrombotic microangiopathy (TMA; n = 17); and nonspecific pathological changes (n = 14). Thirty-nine patients (52%) in 21 families (45%) received a genetic diagnosis; 13 cases (72%) with TIKD, 4 (27%) with GN, 6 (55%) with focal segmental glomerulosclerosis/Alport syndrome, and 10 (59%) with TMA and 6 cases (43%) with nonspecific features. Genetic testing resulted in changes in understanding of disease mechanism in 21 individuals (54%) in 12 families (57%). Treatment would have been altered in at least 26% of cases (10/39). CONCLUSIONS: An accurate genetic diagnosis can result in changes in clinical diagnosis, understanding of pathological mechanism, and treatment. NGS should be considered as a complementary diagnostic technique to kidney biopsy in the evaluation of patients with kidney disease.

Renal transplant outcomes in patients with autosomal dominant tubulointerstitial kidney disease.

INTRODUCTION: Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a rare genetic cause of chronic kidney disease (CKD) and end-stage renal disease (ESRD). We aimed to compare renal transplant outcomes in people with ESRD due to ADTKD to those with other causes of renal failure. METHODS: Patients with clinical characteristics consistent with ADTKD by the criteria outlined in the 2015 KDIGO consensus were included. We compared ADTKD transplant outcomes with those of 4633 non-ADTKD renal transplant recipients. RESULTS: We included 31 patients who met diagnostic criteria for ADTKD in this analysis, 23 of whom had an identified mutation (28 were categorized as definite-ADTKD and 3 as suspected ADTKD). Five patients received a second transplant during follow-up. In total, 36 grafts were included. We did not identify significant differences between groups in terms of graft or patient survival after transplantation. Twenty-five transplant biopsies were performed during follow-up, and none of these showed signs of recurrent ADTKD post-transplant. CONCLUSION: In patients with ESRD due to ADTKD, we demonstrate that transplant outcomes are comparable with the general transplant population. There is no evidence that ADTKD can recur after transplantation.

Monogenic causes of chronic kidney disease in adults.

Approximately 500 monogenic causes of chronic kidney disease (CKD) have been identified, mainly in pediatric populations. The frequency of monogenic causes among adults with CKD has been less extensively studied. To determine the likelihood of detecting monogenic causes of CKD in adults presenting to nephrology services in Ireland, we conducted whole exome sequencing (WES) in a multi-centre cohort of 114 families including 138 affected individuals with CKD. Affected adults were recruited from 78 families with a positive family history, 16 families with extra-renal features, and 20 families with neither a family history nor extra-renal features. We detected a pathogenic mutation in a known CKD gene in 42 of 114 families (37%). A monogenic cause was identified in 36% of affected families with a positive family history of CKD, 69% of those with extra-renal features, and only 15% of those without a family history or extra-renal features. There was no difference in the rate of genetic diagnosis in individuals with childhood versus adult onset CKD. Among the 42 families in whom a monogenic cause was identified, WES confirmed the clinical diagnosis in 17 (40%), corrected the clinical diagnosis in 9 (22%), and established a diagnosis for the first time in 16 families referred with CKD of unknown etiology (38%). In this multi-centre study of adults with CKD, a molecular genetic diagnosis was established in over one-third of families. In the evolving era of precision medicine, WES may be an important tool to identify the cause of CKD in adults.

Progressive improvement in short-, medium- and long-term graft survival in kidney transplantation patients in Ireland - a retrospective study.

It is often quoted that while short-term graft survival in kidney transplantation has improved in recent years, it has not translated into a commensurate improvement in long-term graft survival. We considered whether this was true of the entire experience of the national kidney transplant program in Ireland. A retrospective analysis of the National Kidney Transplant Service (NKTS) database was undertaken to investigate patient and graft survival for all adult first deceased donor kidney transplant recipients in Ireland, 1971-2015. Three thousand two hundred and sixty recipients were included in this study. Kaplan-Meier methods were used to estimate survival at each time period post transplant for the various eras of transplantation. Uncensored graft survival has improved over the course of the program in Ireland at various time points despite risk factors for graft failure progressively increasing over successive eras. For example the graft survival at 15 years post transplant has increased from 10% in 1971-1975 to 45% by 1996-2000. Ireland has experienced a progressive improvement in long-term graft survival following kidney transplantation. Whether these trends are attributable to biological or nonbiological factors is unclear but likely involves a combination of both.

Renal transplant outcomes in primary FSGS compared with other recipients and risk factors for recurrence: A national review of the Irish Transplant Registry.

INTRODUCTION: Primary focal segmental glomerular sclerosis (p-FSGS) is commonly complicated by recurrence (r-FSGS) post-transplantation. Our objective was to describe Irish outcomes for transplantation after end-stage renal disease (ESRD) due to p-FSGS, specifically rates of, and treatments for, r-FSGS. PATIENTS AND METHODS: Irish patients with biopsy-proven FSGS were identified from the Irish National Kidney Transplant database (1982-2015). Medical record review was performed to identify predictors of r-FSGS and treatments for r-FSGS. Transplant outcomes were compared to outcomes in all renal transplants performed during the same time period using registry data. Demographic and clinical predictors of r-FSGS were identified. Statistical analysis was performed using Stata (version 13, College Station, TX, USA). RESULTS: Thirty-eight transplant recipients had biopsy-proven p-FSGS, 16 received a second transplant. A total of 3846 transplants formed the comparator group. r-FSGS complicated 60.5% (23/38) of first transplants. Eighty-six percent (10/12) of patients with previous r-FSGS developed recurrent disease after further transplantation. Patients with p-FSGS receiving a first renal transplant had higher rate of graft failure than those with another cause of ESRD (HR 1.9, 95% CI 1.152-3.139). Sixteen patients received immunotherapy for r-FSGS; 12 (86%) had at least partial response, but two (14%) developed significant complications. DISCUSSION: We demonstrate high rates of r-FSGS and describe modest success from with treatments for r-FSGS.

A De Novo Deletion in the Regulators of Complement Activation Cluster Producing a Hybrid Complement Factor H/Complement Factor H-Related 3 Gene in Atypical Hemolytic Uremic Syndrome.

The regulators of complement activation cluster at chromosome 1q32 contains the complement factor H (CFH) and five complement factor H-related (CFHR) genes. This area of the genome arose from several large genomic duplications, and these low-copy repeats can cause genome instability in this region. Genomic disorders affecting these genes have been described in atypical hemolytic uremic syndrome, arising commonly through nonallelic homologous recombination. We describe a novel CFH/CFHR3 hybrid gene secondary to a de novo 6.3-kb deletion that arose through microhomology-mediated end joining rather than nonallelic homologous recombination. We confirmed a transcript from this hybrid gene and showed a secreted protein product that lacks the recognition domain of factor H and exhibits impaired cell surface complement regulation. The fact that the formation of this hybrid gene arose as a de novo event suggests that this cluster is a dynamic area of the genome in which additional genomic disorders may arise.

Urinary Soluble CD163 in Active Renal Vasculitis.

A specific biomarker that can separate active renal vasculitis from other causes of renal dysfunction is lacking, with a kidney biopsy often being required. Soluble CD163 (sCD163), shed by monocytes and macrophages, has been reported as a potential biomarker in diseases associated with excessive macrophage activation. Thus, we hypothesized that urinary sCD163 shed by crescent macrophages correlates with active glomerular inflammation. We detected sCD163 in rat urine early in the disease course of experimental vasculitis. Moreover, microdissected glomeruli from patients with small vessel vasculitis (SVV) had markedly higher levels of CD163 mRNA than did those from patients with lupus nephritis, diabetic nephropathy, or nephrotic syndrome. Both glomeruli and interstitium of patients with SVV strongly expressed CD163 protein. In 479 individuals, including patients with SVV, disease controls, and healthy controls, serum levels of sCD163 did not differ between the groups. However, in an inception cohort, including 177 patients with SVV, patients with active renal vasculitis had markedly higher urinary sCD163 levels than did patients in remission, disease controls, or healthy controls. Analyses in both internal and external validation cohorts confirmed these results. Setting a derived optimum cutoff for urinary sCD163 of 0.3 ng/mmol creatinine for detection of active renal vasculitis resulted in a sensitivity of 83%, specificity of 96%, and a positive likelihood ratio of 20.8. These data indicate that urinary sCD163 level associates very tightly with active renal vasculitis, and assessing this level may be a noninvasive method for diagnosing renal flare in the setting of a known diagnosis of SVV.

Outcomes of kidney transplantation in Alport syndrome compared with other forms of renal disease.

INTRODUCTION: Alport syndrome is an inherited renal disease characterized by hematuria, renal failure, hearing loss and a lamellated glomerular basement membrane. Patients with Alport syndrome who undergo renal transplantation have been shown to have patient and graft survival rates similar to or better than those of patients with other renal diseases. METHODS: In this national case series, based in Beaumont Hospital Dublin, we studied the cohort of patients who underwent renal transplantation over the past 33 years, recorded prospectively in the Irish Renal Transplant Registry, and categorized them according to the presence or absence of Alport syndrome. The main outcomes assessed were patient and renal allograft survival. RESULTS: Fifty-one patients diagnosed with Alport syndrome in Beaumont Hospital received 62 transplants between 1982 and 2014. The comparison group of non-Alport patients comprised 3430 patients for 3865 transplants. Twenty-year Alport patient survival rate was 70.2%, compared to 44.8% for patients with other renal diseases (p = .01). Factors associated with patient survival included younger age at transplantation as well as differences in recipient sex, donor age, cold ischemia time, and episodes of acute rejection. Twenty-year graft survival was 46.8% for patients with Alport syndrome compared to 30.2% for those with non-Alport disease (p = .11). CONCLUSIONS: Adjusting for baseline differences between the groups, patients with end-stage kidney disease (ESKD) due to Alport syndrome have similar patient and graft survival to those with other causes of ESKD. This indicates that early diagnosis and management can lead to favorable outcomes for this patient cohort.

C4 Glomerulopathy: A Disease Entity Associated With C4d Deposition.

Complement-mediated glomerulonephritis, which includes C3 glomerulopathy, is characterized by dominant staining of C3 with minimal or no immunoglobulin deposits on immunofluorescence studies. We describe a new entity of complement-mediated glomerulonephritis that is characterized by bright C4d staining but with no or minimal C3 or immunoglobulin deposits on immunofluorescence studies. We label this entity as C4 glomerulopathy. C4 glomerulopathy includes C4 dense deposit disease and C4 glomerulonephritis. C4 dense deposit disease is characterized by bright C4d staining and dense deposits along glomerular basement membranes. C4 glomerulonephritis is characterized by bright C4d staining and many mesangial electron-dense deposits, with or without rare intramembranous electron-dense deposits. We describe clinical features and kidney biopsy results in a short series of 3 patients to highlight these findings. All 3 patients presented with proteinuria, and 2 patients also had hematuria. Kidney function was preserved in 2 patients, whereas 1 patient presented with declining kidney function. Evaluation for autoimmune disease, infection, and paraprotein yielded negative results in all patients. Complement levels were normal, although 1 patient had borderline low C4 levels. Kidney biopsy showed mesangial proliferative or membranoproliferative glomerulonephritis with bright C4d staining and absent or minimal C1q, C3, and immunoglobulin. Laser microdissection and mass spectrometry of glomeruli in all 3 patients showed large to moderate numbers of spectra matching C4. Furthermore, analysis of amino acid sequences showed that they were localized to the C4d portion of C4, consistent with immunofluorescence findings. Further studies are required to determine the underlying cause. In summary, we describe a novel complement-mediated glomerulonephritis that is characterized by bright glomerular C4d staining with minimal or absent staining for C1q, C3, and immunoglobulin.

Familial MPGN - a case series: a clinical description of familial membranoproliferative glomerulonephritis amongst three Irish families.

Genetic factors have been implicated in the pathogenesis of certain cases of MPGN. Familial cases of all three histological subtypes have been described. Genetic defects in the control of complement pathways appear to be at the root of many hereditary forms of MPGN. Here we describe a series of three families with familial MPGN. We have identified 3 individuals with a diagnosis of idiopathic MPGN, each with a sibling with the same diagnosis. Data collected included age at presentation, histological findings and age at commencement of renal replacement therapy. A family pedigree was generated for each family as well as a description of the long-term clinical course and transplant outcomes of affected individuals. We have identified male and female affected individuals in this series of three families. The progression to end-stage kidney disease was universal amongst affected individuals. The majority of cases were successfully transplanted. Recurrence in a transplanted kidney occurred in only one individual. This series of familial MPGN provides further evidence for a genetic basis for the disease. Additional studies on these three families will further our knowledge of the underlying mutations in hereditary MPGN and contribute to the understanding of complement-mediated renal disease.

Clinical and pathologic characteristics of hereditary apolipoprotein A-I amyloidosis in Ireland.

AIM: Apolipoprotein A-I amyloidosis is a rare, autosomal dominant disorder characterized by progressive accumulation of amyloid fibrils in tissues, leading to renal and hepatic disease. We describe the clinical manifestations and pathologic features of kidney disease in three Irish families. METHODS: This observational study examines all known cases of chronic kidney disease due to hereditary apolipoprotein A-I amyloidosis in Ireland. Patients were identified by physician interview. In all of the affected individuals the disease was caused by the Gly26Arg heterozygous mutation. Immunohistochemistry confirmed that amyloid deposits were composed of apolipoprotein A-I fibrils. Family trees and clinical data were obtained via analysis of patient medical records. RESULTS: The vast majority of affected cases had demonstrable kidney disease, with variable liver disease. Renal disease most commonly manifested as slowly progressive renal impairment with mild proteinuria. In one kindred, a severe, debilitating peripheral neuropathy was common among affected family members. Histology demonstrated tubulointerstitial fibrosis with amyloid deposition in the medulla. There was very high penetrance within affected families. Of five patients who were transplanted, one transplant was lost after 5 years due to recurrent disease. One patient died from sepsis shortly after transplant. CONCLUSION: Hereditary apolipoprotein A-I amyloidosis is characterized by slowly progressive renal disease. Amyloid is deposited in the renal medulla highlighting the need to examine the medulla on renal biopsy. Overall, kidney transplantation conferred a survival advantage.

The utility of a genetic kidney disease clinic employing a broad range of genomic testing platforms: experience of the Irish Kidney Gene Project.

BACKGROUND AND AIMS: Genetic testing presents a unique opportunity for diagnosis and management of genetic kidney diseases (GKD). Here, we describe the clinical utility and valuable impact of a specialized GKD clinic, which uses a variety of genomic sequencing strategies. METHODS: In this prospective cohort study, we undertook genetic testing in adults with suspected GKD according to prespecified criteria. Over 7 years, patients were referred from tertiary centres across Ireland to an academic medical centre as part of the Irish Kidney Gene Project. RESULTS: Among 677 patients, the mean age was of 37.2 ± 13 years, and 73.9% of the patients had family history of chronic kidney disease (CKD). We achieved a molecular diagnostic rate of 50.9%. Four genes accounted for more than 70% of identified pathogenic variants: PKD1 and PKD2 (n = 186, 53.4%), MUC1 (8.9%), and COL4A5 (8.3%). In 162 patients with a genetic diagnosis, excluding PKD1/PKD2, the a priori diagnosis was confirmed in 58% and in 13% the diagnosis was reclassified. A genetic diagnosis was established in 22 (29.7%) patients with CKD of uncertain aetiology. Based on genetic testing, a diagnostic kidney biopsy was unnecessary in 13 (8%) patients. Presence of family history of CKD and the underlying a priori diagnosis were independent predictors (P < 0.001) of a positive genetic diagnosis. CONCLUSIONS: A dedicated GKD clinic is a valuable resource, and its implementation of various genomic strategies has resulted in a direct, demonstrable clinical and therapeutic benefits to affected patients.

Karyomegalic Interstitial Nephritis: Cancer Risk Following Transplantation.

A brother and sister presented individually in their forties with progressive renal failure, bronchiectasis and mild derangements of their liver function tests. Both developed end-stage renal disease before the age of 50. Both siblings were found to carry a pathogenic, recessive, compound heterozygote mutation in the gene FAN1, which causes karyomegalic interstitial nephritis. Both siblings underwent renal transplantation. The sister developed small cell carcinoma of the lung 18 months after transplantation. Despite intensive chemotherapy she died 6 months later. Six years after transplant, the brother has developed prostate cancer and over 30 individual skin cancers. To our knowledge, only 6 other patients with FAN1 mutations have undergone solid organ transplantation. Outcomes have been poor, with only 3 patients surviving beyond 1 year. While cancer is a significant risk for all patients in the post-transplant period, only 0.01% of patients develop >10 skin cancers. Transplantation may be an unrecognised risk in patients with FAN1 mutations.

Diagnostic utility of genetic testing in patients undergoing renal biopsy.

High-throughput DNA testing is becoming established as a standard diagnostic test in the renal clinic. Previously published studies on cohorts of patients with unexplained chronic kidney disease of a suspected genetic aetiology have suggested a diagnostic yield for genomic sequencing of up to 18%. Here we determine the yield of targeted gene panel in a clinically unscreened cohort of patients referred for percutaneous native renal biopsy. Patients who underwent renal biopsy for investigation of chronic kidney disease were sequenced using a genomic sequencing panel covering 227 genes in which variation is known to be associated with monogenic chronic kidney disease (CKD). Candidate disease-causing variants were assessed for pathogenicity using guidelines from the American College for Medical Genetics and Genomics. Fifty CKD patients were recruited and sequenced. A molecular diagnosis was obtained for two patients (4%). A molecular diagnosis is possible using genomic testing in ∼4% of clinically unscreened patients undergoing renal biopsy. Genetic screening may be useful for diagnosis in a subset of CKD patients but is most valuable when applied to patients with suspected heritable forms of kidney disease.

An Exome Sequencing Study of 10 Families with IgA Nephropathy.

BACKGROUND: Immunoglobulin A nephropathy (IgAN) is a heterogeneous disorder with a strong genetic component. The advent of whole exome sequencing (WES) has accelerated the discovery of genetic risk factors underlying familial disorders. OBJECTIVES: We set out to test whether damaging variants in known kidney disease genes explain a proportion of IgAN cases recruited in Ireland. METHODS: We performed WES in 10 Irish families with multiple affected members having kidney disease where at least one member had biopsy confirmed IgAN. Candidate variants were identified based on being shared between affected family members, minor allele frequency, function and predicted pathogenicity. Pathogenicity of variants was determined according to American College of Medical Genetics and Genomics guidelines. RESULTS: We detected candidate variants in 3 of 10 families. We identified a likely pathogenic variant in COL4A5 in one family and a variant of unknown significance (VUS) in COL4A3 in another. Variants in COL4A5 and COL4A3 are known to cause Alport syndrome. In the third family, we identified a VUS in LMX1B, a gene associated with Nail-patella syndrome. CONCLUSIONS: We identified a number of cases of familial IgAN where the families harbored variants in known kidney disease-related genes indicating that potentially a number of cases of familial IgAN are mistaken for other familial kidney disorders. However, the majority of families studied did not carry a candidate variant in a known kidney disease causing gene indicating that there may be >1 underlying genetic mechanism present in these families.

Dual kidney transplantation with organs from extended criteria cadaveric donors.

PURPOSE: The critical shortage of kidneys available for transplantation has led to alternate strategies to expand the pool. Transplantation of the 2 kidneys into a single recipient using organs suboptimal for single kidney transplantation was suggested. We assessed results in 24 grafts allocated for dual kidney transplantation vs those in a control group of 44 designated for single kidney transplantation. Each group underwent pretransplant biopsy and recipients were age matched. MATERIALS AND METHODS: Dual kidney transplantation was done in 24 of 1,091 transplants (2.1%) from 2001 to 2008. In patients with dual kidney transplant vs single kidney transplant mean recipient age was 60.6 vs 60.8 years, mean HLA-A, B and DR mismatches were 3.3 vs 2.9, and average patient waiting time was 15.6 vs 13.9 months. All grafts were perfused with University of Wisconsin solution with a mean cold ischemia time of 17.9 hours. On donor dual kidney biopsy in the dual kidney transplant vs single kidney transplant group the average fibrosis rate was 30% (range 25% to 45%) vs 25% (range 3% to 40%) and the glomerulosclerosis rate was 17.9% (range 3.2% to 40.7%) vs 7.1% (range 0% to 50%). RESULTS: Good postoperative renal function was noted in 14 dual kidney transplantation cases. Acute tubular necrosis requiring dialysis developed in 5 patients as well as acute rejection in 1. Two dual kidney recipients (8%) died in the postoperative period with no single kidney deaths. One patient underwent bilateral transplantectomy. Mean anesthesia time was longer in the dual group (371 vs 212 minutes). Patient and graft survival was equivalent to that in the control group at 36 months. CONCLUSIONS: Careful selection of marginal kidneys based on clinical and histological criteria allows the use of organs that would not ordinarily be sufficient for transplantation with acceptable outcomes. This is a valid strategy to address the organ shortage.