Progressive liver, kidney, and heart degeneration in children and adults affected by TULP3 mutations.

Organ fibrosis is a shared endpoint of many diseases, yet underlying mechanisms are not well understood. Several pathways governed by the primary cilium, a sensory antenna present on most vertebrate cells, have been linked with fibrosis. Ciliopathies usually start early in life and represent a considerable disease burden. We performed massively parallel sequencing by using cohorts of genetically unsolved individuals with unexplained liver and kidney failure and correlated this with clinical, imaging, and histopathological analyses. Mechanistic studies were conducted with a vertebrate model and primary cells. We detected bi-allelic deleterious variants in TULP3, encoding a critical adaptor protein for ciliary trafficking, in a total of 15 mostly adult individuals, originating from eight unrelated families, with progressive degenerative liver fibrosis, fibrocystic kidney disease, and hypertrophic cardiomyopathy with atypical fibrotic patterns on histopathology. We recapitulated the human phenotype in adult zebrafish and confirmed disruption of critical ciliary cargo composition in several primary cell lines derived from affected individuals. Further, we show interaction between TULP3 and the nuclear deacetylase SIRT1, with roles in DNA damage repair and fibrosis, and report increased DNA damage ex vivo. Transcriptomic studies demonstrated upregulation of profibrotic pathways with gene clusters for hypertrophic cardiomyopathy and WNT and TGF-ß signaling. These findings identify variants in TULP3 as a monogenic cause for progressive degenerative disease of major organs in which affected individuals benefit from early detection and improved clinical management. Elucidation of mechanisms crucial for DNA damage repair and tissue maintenance will guide novel therapeutic avenues for this and similar genetic and non-genomic diseases.

Protocol Biopsies in Pediatric Liver Transplantation Recipients Improve Graft Histology and Personalize Immunosuppression.

OBJECTIVES: Protocol liver biopsies (PLBs) are part of the follow-up program at many pediatric liver transplant centers, but the impact on clinical decision-making and allograft histology following adjustments of immunosuppression (IS) after PLB has not been thoroughly analyzed. METHODS: Following our previous single-center cohort study, we have now evaluated histological findings of 178 PLBs of 118 pediatric patients transplanted at our center between 1998 and 2017. In particular, we focused on the changes in allograft histology in the follow-up biopsy of a subgroup of 22 patients, in which the histologic findings led to an adjustment of immunosuppressive therapy. All biopsies of this sub-study group were reevaluated by an experienced pathologist. RESULTS: The overall frequency and severity of fibrosis increased over time after orthotopic liver transplantation. Patients with donor-specific antibodies (DSAs) had a higher prevalence of fibrosis than DSA-negative patients. Graft inflammation decreased significantly after intensifying IS, but renal function needs to be monitored. A significant increase in fibrosis was detected in children with reduced IS. CONCLUSION: The adjustment of IS following PLBs has a significant impact on allograft histology. Since chronic inflammatory changes may lead to graft failure, adjustment of IS seems to be of major importance for the long-term outcome.

Presence of donor specific HLA class 2 antibodies (DSA class 2) is associated with development of graft fibrosis more than 10 years after liver transplantation-a retrospective single center study.

Here the impact of donor specific human leukocyte antigen (HLA) class 2 antibodies (DSA cl 2) on long term outcome after liver transplantation (LT) was investigated. Altogether 156 (44 pediatric and 112 adult) LT recipients were included in the study. Graft fibrosis was assessed by liver elastography and biopsy. DSA cl 2 were determined by Luminex technology. 46% of LT recipients were positive for DSA cl 2 after a median follow-up of 15 years. In the multivariate analysis DSA cl 2 were significantly associated with immunosuppressive monotherapy (OR 5.42; 95% CI: 1.02-28.90; p = .048). Compared to DSA cl 2 negative patients, positive recipients had significantly more graft fibrosis based on the liver stiffness (mean 9.4 ± 9.0 kPa vs. 6.5 ± 6.3 kPa; p < .002) and fibrosis stages determined by liver elastography (p = .016) and the performed liver biopsies (p = .002). Also, a significantly higher incidence of chronic rejections (11% vs. 2%; p = .045) and graft losses (6% vs. 0%; p = .043) were found. In the multivariate regression analysis DSA cl 2 were significantly associated with graft fibrosis (OR 4.57; 95% CI 1.59-13.10; p = .005). So, these data suggest that development of DSA cl 2 occurs more often with immunosuppressive monotherapy and may ultimately result in chronic rejection and graft fibrosis.

Psychosocial situation, adherence, and utilization of video consultation in young adult long-term pediatric liver transplant recipients during COVID-19 pandemic.

BACKGROUND: Young adults who underwent liver transplantation in childhood (YALTs) are highly vulnerable to non-adherent behavior and psychosocial problems. During the COVID-19 pandemic, special efforts may be necessary to maintain contact with these patients and offer support. This can be achieved through the use of telemedicine. The study's objective was to assess adherence and the psychosocial situation of YALTs during the COVID-19 pandemic in Germany and to evaluate the utilization of video consultations. METHODS: In May 2020, a questionnaire was sent to YALTs treated at the Hamburg University Transplant Center, accompanied by the offer of video appointments with the attending physician. The questionnaire included the Generalized Anxiety Disorder Scale 7, the Patient Health Questionnaire 2, and questions compiled by the authors. RESULTS: Of 98 YALTs, 12% used the video consultation, while 65% had an in-person appointment. The 56 patients who completed the questionnaire did not report reduced medication adherence during the pandemic, but 40% missed follow-up visits with their primary care physician or check-up laboratory tests. About 70% of YALTs were afraid to visit their physician and the transplant center, and 34% were afraid of a SARS-CoV-2 infection. Mental health and well-being were unimpaired. CONCLUSIONS: During the COVID-19 pandemic, YALTs in our study did not show an increased need for psychosocial support, but a majority were afraid to attend medical appointments, and 40% reported lower appointment adherence. Acceptance of video consultations was lower than expected. The reasons for this need to be further investigated in order to optimize care.

Alloimmunity and Cholestasis After Liver Transplantation in Children With Progressive Familial Intrahepatic Cholestasis.

OBJECTIVES: Bile salt export pump (BSEP) deficiency is an important reason for chronic cholestasis leading to liver transplantation (LT) in early childhood. The underlying pathology is a dysfunction of BSEP due to various mutations in the ABCB11 gene. Cases of clinical recurrence after LT due to alloantibodies directed against BSEP (antibody-induced BSEP deficiency [AIBD]) have been reported. Most of these patients could be controlled by intensified immunosuppression. METHODS: We here report on 3 children with BSEP-deficiency and end-stage liver disease, which developed AIBD after LT refractory to extensive immunosuppressive and immunomodulatory treatments; retransplantation was necessary in all 3 patients. In 1 patient, a stem cell transplantation was performed successfully. RESULTS: AIBD seems to be induced by triggering factors such as initial impaired graft function or infections after LT. CONCLUSIONS: The underlying mutation may play a role in this process. Intensifying immunosuppression may be able to control AIBD, but some cases seem to be refractory to treatment and require retransplantation. Stem cell transplantation may provide a new therapeutic option for cases refractory to conservative treatment.

Allogeneic haematopoietic stem cell transplantation eliminates alloreactive inhibitory antibodies after liver transplantation for bile salt export pump deficiency.

Progressive familial intrahepatic cholestasis 2 is an autosomal-recessive disorder caused by mutations in the ABCB11 gene, which encodes the bile salt export pump (BSEP). Recurrence of BSEP deficiency after liver transplantation is caused by the development of anti-BSEP antibodies. Antibody-induced BSEP deficiency is typically treated by increasing immunosuppressive therapy. We report, in a child, the first case of allogeneic haematopoietic stem cell transplantation for antibody-induced BSEP deficiency that was refractory to intensive pharmacological immunosuppression and immunoadsorption. After haematopoietic stem cell transplantation, anti-BSEP antibodies were cleared from the patient's serum and later from the canalicular space of the liver graft.

Long-term outcomes after liver transplantation for deoxyguanosine kinase deficiency: a single-center experience and a review of the literature.

Deoxyguanosine kinase (DGUOK) deficiency is a well-known cause of hepatocerebral mitochondrial DNA depletion syndromes, which include a broad spectrum of clinical presentations. Affected patients often develop life-threatening liver failure, but the benefits of liver transplantation (LT) are controversial because of the frequently severe neurological involvement due to the underlying mitochondrial disease. We describe the long-term clinical course of 2 patients from our institution and provide an update on their outcomes after LT with this condition. Another 12 pediatric patients were identified through a systematic search of the literature. All 14 reported patients underwent transplantation in infancy despite mild to moderate neurological impairment in some cases. The 2 DGUOK-deficient patients from our center displayed liver failure and mild to moderate neurological involvement. At the time of this writing, they had been followed for 5 and 8 years after LT, both patients were alive, and they had only mild neurological symptoms. Three of the 12 patients identified through the literature review survived for a long time (17, 12, and 23 years); 8 died during early follow-up; and for 1 patient, no follow-up information was available. The 1-year survival rate was 64%; 36% survived for more than 5 years. The long-term survivors had good quality of life. In conclusion, although survival after LT for DGUOK deficiency is lower than survival after LT for other indications, a significant proportion of patients benefit from LT with long-term survival and a stable neurological situation despite initial neurological abnormalities. Nevertheless, a decision to carry out LT for patients with DGUOK deficiency remains difficult because neurological symptoms may occur and worsen after LT despite their absence before transplantation.

Developments in pediatric liver transplantation since implementation of the new allocation rules in Eurotransplant.

Liver allocation in the Eurotransplant (ET) region has changed from a waiting time to an urgency-based system using the model of end-stage liver disease (MELD) score in 2006. To allow timely transplantation, pediatric recipients are allocated by an assigned pediatric MELD independent of severity of illness. Consequences for children listed at our center were evaluated by retrospective analysis of all primary pediatric liver transplantation (LTX) from deceased donors between 2002 and 2010 (110 LTX before/50 LTX after new allocation). Of 50 children transplanted in the MELD era, 17 (34%) underwent LTX with a high-urgent status that was real in five patients (median lab MELD 22, waiting time five d) and assigned in 12 patients (lab MELD 7, waiting time 35 d). Thirty-three children received a liver by their assigned pediatric MELD (lab MELD 15, waiting time 255 d). Waiting time in the two periods was similar, whereas the wait-list mortality decreased (from about four children/yr to about one child/yr). One- and three-yr patient survival showed no significant difference (94.5/97.7%; p = 0.385) as did one- and three-yr graft survival (80.7/75.2%; and 86.5/82%; p = 0.436 before/after). Introduction of a MELD-based allocation system in ET with assignment of a granted score for pediatric recipients has led to a clear priorization of children resulting in a low wait-list mortality and good clinical outcome.

Outcome of liver re-transplantation in children--impact and special analysis of early re-transplantation.

In case of graft failure, re-LTX is the only life-saving option but it has been associated with inferior results. This study analyzes the outcome following pediatric re-LTX with a main focus on the timely relation between initial transplant and re-LTX. All pediatric LTX at our institution between 2000 and 2010 divided into patients with primary LTX and patients undergoing re-LTX early (≤30 days) or late (>30 days) after previous LTX were analyzed. Two hundred and ninety-eight primary LTX(79%), 33 early (9%), and 46 late (12%) re-LTX were performed. Patient/graft survival was significantly worse for children undergoing early re-LTX compared to primary LTX and late re-LTX (p = 0.024/0.001 and p = 0.015/0.03). One-/five-yr graft survival rates were 66%/49% for early re-LTX compared to 86%/76% for late re-LTX and 90%/74% for primary LTX. The inferior results in children undergoing early re-LTX were due to events occurring in the first six months with similar survival thereafter. No difference in outcome was evident after adjustment of the groups for high-urgency status. Outcome was excellent for primary LTX and late re-LTX, supporting late re-LTX in children. Early re-LTX takes an elevated risk of early graft loss and patient death; however, beyond the early postoperative period, the outcome was comparable.

Cytokine concentrations and regulatory T cells in living donor and deceased donor liver transplant recipients.

Outcomes of pediatric liver transplantation have constantly improved in the last decade. Living-related liver transplantation does not seem to improve long-term outcomes following liver transplantation, but few studies have evaluated immunological parameters of the alloimmune response after living vs. deceased donor organ transplantation. We analyzed numbers of regulatory T cells, lymphocyte subsets, and serum cytokine concentrations in 12 pediatric recipients of living-related liver transplants and in 28 pediatric recipients of deceased donor organs during their annual follow-ups. Transplant recipients who underwent living donor organ transplantation had significantly higher numbers of regulatory T cells and IL-4 serum concentrations than recipients of deceased donor organs; both of these factors are associated with beneficial outcomes and transplantation tolerance. Living-related liver transplantation may have potentially beneficial immunological aspects, although long-term outcomes do not seem to be better in recipients of living donor organs than in recipients of deceased donor organs. Further studies are needed to compare immunological aspects of the two transplant procedures.

Liver allograft pathology in healthy pediatric liver transplant recipients.

Liver transplantation offers excellent results for children with end-stage liver disease, and efforts should be directed toward maintaining long-term graft health. We evaluate graft pathology in healthy pediatric transplant recipients with low-maintenance immunosuppressive medications to assess whether protocol biopsies are helpful for adapting immunosuppression and protecting long-term graft function. Liver biopsies were performed on 60 healthy pediatric liver transplant recipients, and histological findings were correlated with laboratory, serological, and radiological results. Fourteen patients (23%) were diagnosed with acute or early chronic rejection, and immunosuppressive medications were increased in these children. Liver function tests did not correlate with histological findings. The incidence of fibrosis was 36% in transplant recipients five or more years after liver transplantation. We observed an unexpectedly high prevalence of rejection and fibrosis in children with no laboratory abnormalities, which led to changes in their immunosuppressive medications. Scheduled biopsies appear to be useful in pediatric transplant recipients with low immunosuppressive medications for early detection of morphological changes in liver transplants. Further studies are needed to evaluate whether adaption of immunosuppression helps to reduce tissue damage and the incidence of allograft dysfunction in the long term.

Peripheral blood biomarkers for the characterization of alloimmune reactivity after pediatric liver transplantation.

Individualization of immunosuppressive medications is an important objective in transplantation medicine. Reliable biomarkers to distinguish between patients dependent from intensive immunosuppressive therapy and those where therapy can be minimized among pediatric transplant recipients receiving immunosuppressive medications are still not established. We evaluated the potential of cross-sectional quantification of regulatory T cells, lymphocyte subsets, and cytokine concentrations as biomarkers in 60 pediatric liver transplant recipients with AR, CR, or normal graft function and in 11 non-transplanted patients. Transplant recipients presenting with AR had significantly higher CD8+ T-cell counts, significantly higher concentrations of IL-2, and increased levels of IFN-γ compared with asymptomatic patients or controls. Regulatory T-cell numbers did not differ between children with rejection and children with good graft function. A tendency toward increased concentrations of IL-4 and TGF-ß was detected in transplant recipients with good graft function. Cross-sectional parameters of peripheral regulatory T cells in pediatric liver transplant recipients do not seem to be valuable biomarkers for individualizing immunosuppressive therapy prior to the weaning process. Lymphocyte subsets, IL-2, IFN-γ, IL-4, and TGF-ß serum concentrations may be helpful to identify children in whom immunosuppression can be reduced or discontinued.

Experience with the mTOR Inhibitor Everolimus in Pediatric Liver Graft Recipients.

INTRODUCTION: Immunosuppression after pediatric liver transplantation remains a major challenge. MTOR inhibitors provide a promising therapeutic approach in combination with reduced CNI after transplantation. However, there are still few data regarding their use in children. PATIENTS: We analyzed 37 patients with a median age of 10 years, who received Everolimus for one or more of the following indications: I = chronic graft dysfunction (n = 22); II = progressive renal impairment (n = 5); III = non-tolerable side effects with previous immunosuppressive medication (n = 6); and IV = malignancies (n = 10). The median follow-up time was 36 months. RESULTS: Patient survival was 97%, and graft survival 84%, respectively. Stabilization of graft function was observed in 59% in subgroup 1, with 18.2% ultimately requiring retransplantation. No patient in subgroup IV developed recurrence of his primary tumor or PTLD by the endpoint of the study. Side effects were observed in 67.5% of the study patients, with infections being the most frequent (n = 20; 54.1%). There were no relevant effects on growth and development. CONCLUSION: Everolimus seems to be a treatment option in selected pediatric liver graft recipients for whom other regimens are not suitable. Overall, the efficacy was good and the side effect profile appeared to be acceptable.

High prevalence of renal dysfunction in children after liver transplantation: non-invasive diagnosis using a cystatin C-based equation.

BACKGROUND: Chronic kidney disease (CKD) has been increasingly shown to be a negative prognostic factor after liver transplantation (Ltx). Creatinine-based glomerular filtration rate (GFR) formulas are notoriously insensitive. In children, non-invasive determination of GFR by measurement of serum cystatin C is feasible and repeatedly correlated to the gold standards of GFR measurements. The aim of our study was to determine GFR using cystatin C (GFR(cys)) in comparison with conventional calculated creatinine clearance (GFR(crea)) in the long-term follow-up after paediatric liver transplantation (pLtx) in a large number of patients. METHODS: GFR of 168 children following liver transplantation was determined using cystatin C (GFR(cys)) and the Schwartz formula (GFR(crea)). In order to evaluate risk factors for CKD, a logistic regression analysis was performed. A multivariate model was applied to assess the impact of immunosuppressive treatment. RESULTS: The mean follow-up after transplantation was 7.8 (0.44-15.72) years. Due to a high overestimation of GFR as demonstrated in a Bland-Altman plot, only three patients with CKD stages 2-3 were detected with GFR(crea) compared with 34 with GFR(cys) (P < 0.001). Thus, prevalence of CKD with GFR((cys)) < 90 mL/min/1.73 m2; was 30.4%, 7.6% and 27% in patients with 5, 10 and > 10 years of follow-up, respectively. Patients on cyclosporine had a significantly lower GFR than patients on tacrolimus. Logistic regression analysis did not show any significant risk factor for the development of CKD. CONCLUSIONS: The cystatin C equation is a non-invasive and sensitive diagnostic tool to detect renal dysfunction in children after Ltx at an early stage. The choice of first-line calcineurin inhibitor has an important impact on the development of CKD.

Liver transplantation in children using organs from young paediatric donors.

Nowadays, most paediatric liver transplant recipients receive a split or other technical variant graft from adult deceased or live donors, because of a lack of available age- and size matched paediatric donors. Few data are available, especially for liver grafts obtained from very young children (<6 years). We analysed all paediatric liver transplantations between 1989 and 2009. Recipients were divided into five groups (1-5) depending on donor age (<1, ≥1 to <6, ≥6 to <16, ≥16 to <45, ≥45 years). Overall, 413 paediatric liver transplantations from deceased donors were performed; 1- and 5-year graft survival rates were 75%, 80%, 78%, 81%, 74% and 75%, 64%, 70%, 67%, 46%, and 1- and 5-year patient survival rates were 88%, 91%, 90%, 89%, 78% and 88%, 84%, 84%, 83%, 63% for groups 1-5, respectively, without significant difference. Eight children received organs from donors younger than 1 year and 45 children received organs from donors between 1 and 6 years of age. Overall, vascular complications occurred in 13.2% of patients receiving organs from donors younger than 6 years. Analysis of our data revealed that the usage of liver grafts from donors younger than 6 years is a safe procedure. The outcome was comparable with grafts from older donors with excellent graft and patient survival, even for donors younger than 1 year.

The use of everolimus in pediatric liver transplant recipients: first experience in a single center.

The role of mTOR inhibitors, such as EVL, has not been established for pediatric liver transplant recipients up to now, although data from adult solid organ graft transplantation are very promising. Major complications following pediatric liver transplantation in the long-term course include chronic graft rejection and CNI-derived nephrotoxicity. The purpose of our study was to report first results using EVL as a rescue therapy in pediatric liver transplant recipients for the following indications: chronic graft dysfunction n=12, suspected CNI toxicity n=3, hepatoblastoma n=2, and recurrence of primary sclerosing cholangitis post-Ltx n=1. Four patients with chronic graft dysfunction developed completely normal liver function tests using EVL, six patients showed partial improvement, and two patients did not respond at all. One patient with CNI-induced nephropathy showed a slightly improved GFR. Both patients with hepatoblastoma did not develop any metastasis post-Ltx. First experience with EVL in pediatric liver transplant recipients shows promising results in patients with chronic graft failure when standard immunosuppression has failed. The future role of EVL in immunosuppressive protocols for children post-Ltx has to be proven by controlled clinical trials.

Impact of donor-specific antibodies on long-term graft survival with pediatric liver transplantation.

BACKGROUND: In a previous paper, we reported a high prevalence of donor-specific antibody (DSA) in pediatric patients with chronic rejection and expressed the need for confirmation of these findings in a larger cohort. AIM: To clarify the importance of DSAs on long-term graft survival in a larger cohort of pediatric patients. METHODS: We performed a retrospective analysis of 123 pediatric liver transplantation (LT) recipients who participated in yearly follow-ups including Luminex testing for DSA at our center. The cohort was split into two groups according to the DSA status (DSA-positive n = 54, DSA-negative n = 69). Groups were compared with regard to liver function, biopsy findings, graft survival, need for re-LT and immunosuppressive medication. RESULTS: DSA-positive pediatric patients showed a higher prevalence of chronic rejection (P = 0.01), fibrosis (P < 0.001) and re-transplantation (P = 0.018) than DSA-negative patients. Class II DSAs particularly influenced graft survival. Alleles DQ2, DQ7, DQ8 and DQ9 might serve as indicators for the risk of chronic rejection and/or allograft fibrosis. Mean fluorescence intensity levels and DSA number did not impact graft survival. Previous episodes of chronic rejection might lead to DSA development. CONCLUSION: DSA prevalence significantly affected long-term liver allograft performance and liver allograft survival in our cohort of pediatric LT. Screening for class II DSAs in combination with assessment of protocol liver biopsies for chronic antibody-mediated rejection improved early identification of patients at risk of graft loss.

Impact of hepatopathy in pediatric patients after surgery for complex congenital heart disease.

Patients undergoing complex pediatric cardiac surgery in early infancy are at risk of postoperative secondary end-organ dysfunction. The aim of this study was to determine specific risk factors promoting the development of peri- and postoperative hepatopathy after surgery for congenital heart disease. In this retrospective study, we identified 20 consecutive patients operated between 2011 and 2019 from our institutional cohort who developed significant postsurgical hepatic dysfunction. These patients were compared to a control group of 30 patients with comparable initial cardiac conditions and STS-EACTS risk score. Patients who developed hepatopathy in the intensive care unit have chronic cholestasis and decreased liver synthesis. The impact of postoperative hepatopathy on morbidity was marked. In six patients (30%), liver transplantation was executed as ultima ratio, and two (10%) were listed for liver transplantation. The overall mortality related to postoperative hepatopathy is high: We found nine patients (45%) having severe hepatopathy and mostly multiple organ dysfunction who died in the postoperative course. According to risk analysis, postoperative right and left heart dysfunction in combination with a postoperative anatomical residuum needing a re-operation or re-intervention in the postoperative period is associated with a high risk for the development of cardiac hepatopathy. Furthermore, postoperative complications (pleural effusion, heart rhythm disorders, etc.), postoperative infections, and the need for parenteral nutrition also raise the risk for cardiac hepatopathy. Further investigations are needed to reduce hepatic complications and improve the general prognosis of such complex patients.

Value of ultrasound-guided percutaneous liver biopsy in children following liver transplantation.

OBJECTIVES: Pediatric liver transplant recipients often need to undergo liver biopsies for the detection and specification of complications such as acute or chronic graft rejection, infection, or drug toxicity. Complications resulting from liver biopsy are rare. The aim of our single-center retrospective study was to report on liver biopsy-related complications and, moreover, to assess the significance of histological findings in correlation with the suspected diagnosis. PATIENTS AND METHODS: Overall, 120 liver biopsies from 67 children were performed and analyzed. All of the biopsies were performed with ultrasound guidance using midazolam and ketamine. RESULTS: The overall incidence of complications was 5.0%, but most of these complications were mild. In 2 cases, however, the complications were severe and required surgical intervention in addition to further medical treatment.In about 92% of the cases, liver histology confirmed the previously suspected diagnosis based on clinical and clinical laboratory indications. CONCLUSIONS: We concluded that postliver transplantation liver biopsy in children seldom provides unexpected results and, even using ultrasound guidance, has led, albeit rarely, to serious complications. We therefore now accept potential delay in treatment and reserve liver biopsy for patients who fail to respond to therapy based on clinical judgment.

Prevalence of polyomavirus viruria (JC virus/BK virus) in children following liver transplantation.

BKV infection is a potential cause of renal dysfunction in non-renal organ transplant recipients. JCV is the causative agent of PML. Furthermore, polyomaviruses are tumor inducing viruses and molecular data suggest an association with malignancies among solid organ transplant patients. So far, there are no studies analyzing polyomavirus viruria following Ltx in children. We performed a prospective prevalence study at a mean of 2187 (range 20-5671) days after transplantation in 100 consecutive children admitted for the routine follow-up examination post-Ltx. The urine was screened for BKV and JCV DNA by using PCR in each case. A plasma analysis by PCR was also done if more than 100,000 DNA copies/mL urine were detected. BKV or JCV viruria was found in 19% (n = 19) of our patients. All patients were free of clinical signs of viral infection, PML, or nephropathy. GFR was normal in 97% of patients and we found no statistical difference of kidney function between patients with and without BKV/JCV viruria. The extent of immunosuppressive therapy had no influence on the polyomavirus viruria. Overall, we found a higher prevalence of polyomavirus viruria in our pediatric liver transplant recipients than reported in adult patients.