Transplantation procedures in children with primary hyperoxaluria type 1: outcome and longitudinal growth. Transplantation. 2009;87:1415-1421. [PMID: 19424045 DOI: 10.1097/tp.0b013e3181a27939]

Liver Transplantation in Primary Hyperoxaluria: A Single-Center 10-Year Experience

BACKGROUND

Primary hyperoxalurias (PHs) are rare inborn errors of metabolism caused by a deficiency of hepatic enzymes, leading to excessive urinary oxalate excretion and the overproduction of oxalate, which accumulates in various organs. If left untreated, PHs can cause serious morbidity, end-stage kidney disease (ESKD), and mortality. Liver transplantation (LT) is a recognized treatment option for children with these diseases. This study aimed to analyze the outcome of PHs disease post-LT from a single center in Iran.

METHODS

This retrospective, single-center study was conducted at the Shiraz Transplant Center from 2012 to 2023, focusing on liver transplant recipients with PH. We evaluated long-term outcomes and post-transplantation results for both deceased donor liver transplantation (DDLT) and living donor liver transplantation (LDLT). Biochemical lab results (pre- and post-transplantation), perioperative data, surgical procedures, transplantation outcomes, and recipient and donor characteristics were reported. Kaplan-Meier survival analysis was used to assess graft and patient survival.

RESULTS

33 recipients with LT (LDLT, n = 6; DDLT, n = 27) were included. The median age at the time of transplantation was 8 years (range: 3-18 years). Following liver transplantation, all of the patients had normalization of liver enzymes. Urine oxalate levels gradually decreased from 198 to 51 (< 45 mg/1.73 m2/day). Among the 33 patients, eight experienced episodes of acute rejection, and five developed chronic rejection. Eight patients underwent kidney transplantation before liver transplantation, while 21 patients initially received liver transplantation. 26 patients survived and remained in good health during a median follow-up period of 7 years (range: 1.5-11 years). For patients with PHs, the survival rates at 6 months, 1 year, 3 years, and 5 years were 100%, 97%, 94%, and 85%, respectively. The graft survival for patients was 100%, 100%, 97%, and 97% at 6 months, 1 year, 3 years, and 5 years, respectively.

CONCLUSIONS

PHs is a rare metabolic disorder, and LT significantly improves both survival and quality of life for affected patients. In our cohort, the majority of patients exhibited favorable long-term outcomes, along with a notable reduction in urine oxalate levels post-transplantation. However, challenges persist, including graft shortages and the risk of renal graft loss due to oxalosis, which continue to affect overall treatment outcomes. These findings highlight the importance of close monitoring and multidisciplinary care in managing PH patients' post-transplant.

Simultaneous or sequential kidney-liver transplantation in primary hyperoxaluria

BACKGROUND

Primary hyperoxaluria type 1 is responsible for pediatric kidney failure in 1 to 2% of cases. Novel therapies based on RNA interference are changing the natural history of the disease. However, for those who do progress to kidney failure, and for patients living in countries that cannot afford these expensive therapies, liver-kidney transplantation may remain the only efficient therapy.

METHODS

The aim of the study was to evaluate the outcome of patients with primary hyperoxaluria type 1 who received simultaneous or sequential liver-kidney transplantation. We retrospectively evaluated 10 patients, five of whom received a simultaneous transplantation, and five underwent sequential transplantation, with a median postponement of the kidney transplantation of 8 months (range 4-20). Among the patients, 5 were from medium-low income countries.

RESULTS

Median follow up was 3.2 years (range 1.6-11). Median estimated glomerular filtration rate at 6 and 12 months was 81.2 (range: 45.7-108.8) and 79.3 ml/min/1.73m2 (range 54.7-112.1) in patients who underwent simultaneous transplantation, and 45.7 (range 34.5-86.7) and 38.3 ml/min/1.73m2 (range 29.9-77.5) in those with sequential transplantation (p:NS). Biopsies performed at 6 and 12 months showed precipitation of calcium oxalate crystals in 7 patients, demonstrating the recurrence of deposition despite the delay between liver and kidney transplantation. No differences in kidney function or in post-transplant renal oxalate precipitation were observed between patients that underwent bilateral nephrectomy and those who did not. As of their most recent follow up, none of the patients has lost their kidney graft.

CONCLUSIONS

Our study shows that by adapting the transplant strategy to individual cases, patients with primary hyperoxaluria type 1 can be successfully treated.

Long-term outcome after combined or sequential liver and kidney transplantation in children with infantile and juvenile primary hyperoxaluria type 1

Introduction

Combined or sequential liver and kidney transplantation (CLKT/SLKT) restores kidney function and corrects the underlying metabolic defect in children with end-stage kidney disease in primary hyperoxaluria type 1 (PH1). However, data on long-term outcome, especially in children with infantile PH1, are rare.

Methods

All pediatric PH1-patients who underwent CLKT/SLKT at our center were analyzed retrospectively.

Results

Eighteen patients (infantile PH1 n = 10, juvenile PH1 n = 8) underwent transplantation (CLKT n = 17, SLKT n = 1) at a median age of 5.4 years (1.5-11.8). Patient survival was 94% after a median follow-up of 9.2 years (6.4-11.0). Liver and kidney survival-rates after 1, 10, and 15 years were 90%, 85%, 85%, and 90%, 75%, 75%, respectively. Age at transplantation was significantly lower in infantile than juvenile PH1 (1.6 years (1.4-2.4) vs. 12.8 years (8.4-14.1), P = 0.003). Median follow-up was 11.0 years (6.8-11.6) in patients with infantile PH1 vs. 6.9 years (5.7-9.9) in juvenile PH1 (P = 0.15). At latest follow-up kidney and/or liver graft loss and/or death showed a tendency to a higher rate in patients with infantile vs. juvenile PH1 (3/10 vs. 1/8, P = 0.59).

Discussion

In conclusion, the overall patient survival and long-term transplant outcome of patients after CLKT/SLKT for PH1 is encouraging. However, results in infantile PH1 tended to be less optimal than in patients with juvenile PH1.

Long-term outcomes after pre-emptive liver transplantation in primary hyperoxaluria type 1

BACKGROUND

Primary hyperoxaluria type 1 (PH1) is an autosomal recessive disease caused by the liver defect of oxalate metabolism, which leads to kidney failure and systemic manifestations. Until recently, liver transplantation was the only definitive treatment. The timing of liver transplantation can be early, while kidney function is still normal (pre-emptive liver transplantation-PLT), or when the patient reaches stage 5 chronic kidney disease (CKD) and needs combined liver-kidney transplantation. We aimed to determine the long-term kidney outcomes of PLT in PH1 patients.

METHODS

A retrospective single-center study of PH1 patients who were followed in our center between 1997 and 2017. We compared the kidney outcomes of patients who underwent PLT to those who presented with preserved kidney function and did not undergo PLT.

RESULTS

Out of 36 PH1 patients, 18 patients were eligible for PLT (eGFR > 40 mL/min/1.73 m² at the time of diagnosis). Seven patients underwent PLT (PLT group), while 11 continued conservative treatments (PLTn group). In the PLT group, the median eGFR at the time of PLT and at the end of the follow-up period (14-20 years) was 72 (range 50-89) and 104 (range 86-108) mL/min/1.73 m², respectively, and no patient died or reached stage 5 CKD. In the PLTn group, eight patients (72.7%) reached stage 5 CKD (median time to kidney replacement therapy was 11 years), and two patients died from disease complications (18.2%).

CONCLUSIONS

Pre-emptive liver transplantation preserved kidney function in patients with PH1 in our cohort. Early intervention can prevent kidney failure and systemic oxalosis in PH1. A higher resolution version of the Graphical abstract is available as Supplementary information.

Improving Treatment Options for Primary Hyperoxaluria

The primary hyperoxalurias are three rare inborn errors of the glyoxylate metabolism in the liver, which lead to massively increased endogenous oxalate production, thus elevating urinary oxalate excretion and, based on that, recurrent urolithiasis and/or progressive nephrocalcinosis. Frequently, especially in type 1 primary hyperoxaluria, early end-stage renal failure occurs. Treatment possibilities are scare, namely, hyperhydration and alkaline citrate medication. In type 1 primary hyperoxaluria, vitamin B6, though, is helpful in patients with specific missense or mistargeting mutations. In those vitamin B6 responsive, urinary oxalate excretion and concomitantly urinary glycolate is significantly decreased, or even normalized. In patients non-responsive to vitamin B6, RNA interference medication is now available. Lumasiran® is already available on prescription and targets the messenger RNA of glycolate oxidase, thus blocking the conversion of glycolate into glyoxylate, hence decreasing oxalate, but increasing glycolate production. Nedosiran blocks liver-specific lactate dehydrogenase A and thus the final step of oxalate production. Similar to vitamin B6 treatment, where both RNA interference urinary oxalate excretion can be (near) normalized and plasma oxalate decreases, however, urinary and plasma glycolate increases with lumasiran treatment. Future treatment possibilities are on the horizon, for example, substrate reduction therapy with small molecules or gene editing, induced pluripotent stem cell-derived autologous hepatocyte-like cell transplantation, or gene therapy with newly developed vector technologies. This review provides an overview of current and especially new and future treatment options.

Long-Term Transplantation Outcomes in Patients With Primary Hyperoxaluria Type 1 Included in the European Hyperoxaluria Consortium (OxalEurope) Registry

Introduction

In primary hyperoxaluria type 1 (PH1), oxalate overproduction frequently causes kidney stones, nephrocalcinosis, and kidney failure. As PH1 is caused by a congenital liver enzyme defect, combined liver–kidney transplantation (CLKT) has been recommended in patients with kidney failure. Nevertheless, systematic analyses on long-term transplantation outcomes are scarce. The merits of a sequential over combined procedure regarding kidney graft survival remain unclear as is the place of isolated kidney transplantation (KT) for patients with vitamin B6-responsive genotypes.

Methods

We used the OxalEurope registry for retrospective analyses of patients with PH1 who underwent transplantation. Analyses of crude Kaplan–Meier survival curves and adjusted relative hazards from the Cox proportional hazards model were performed.

Results

A total of 267 patients with PH1 underwent transplantation between 1978 and 2019. Data of 244 patients (159 CLKTs, 48 isolated KTs, 37 sequential liver–KTs [SLKTs]) were eligible for comparative analyses. Comparing CLKTs with isolated KTs, adjusted mortality was similar in patients with B6-unresponsive genotypes but lower after isolated KT in patients with B6-responsive genotypes (adjusted hazard ratio 0.07, 95% CI: 0.01–0.75, P = 0.028). CLKT yielded higher adjusted event-free survival and death-censored kidney graft survival in patients with B6-unresponsive genotypes (P = 0.025, P < 0.001) but not in patients with B6-responsive genotypes (P = 0.145, P = 0.421). Outcomes for 159 combined procedures versus 37 sequential procedures were comparable. There were 12 patients who underwent pre-emptive liver transplantation (PLT) with poor outcomes.

Conclusion

The CLKT or SLKT remains the preferred transplantation modality in patients with PH1 with B6-unresponsive genotypes, but isolated KT could be an alternative approach in patients with B6-responsive genotypes.

Transplantation outcomes in patients with primary hyperoxaluria: a systematic review

BACKGROUND

Primary hyperoxaluria type 1 (PH1) is characterized by hepatic overproduction of oxalate and often results in kidney failure. Liver-kidney transplantation is recommended, either combined (CLKT) or sequentially performed (SLKT). The merits of SLKT and the place of an isolated kidney transplant (KT) in selected patients are unsettled. We systematically reviewed the literature focusing on patient and graft survival rates in relation to the chosen transplant strategy.

METHODS

We searched MEDLINE and Embase using a broad search string, consisting of the terms 'transplantation' and 'hyperoxaluria'. Studies reporting on at least four transplanted patients were selected for quality assessment and data extraction.

RESULTS

We found 51 observational studies from 1975 to 2020, covering 756 CLKT, 405 KT and 89 SLKT, and 51 pre-emptive liver transplantations (PLT). Meta-analysis was impossible due to reported survival probabilities with varying follow-up. Two individual high-quality studies showed an evident kidney graft survival advantage for CLKT versus KT (87% vs. 14% at 15 years, p<0.05) with adjusted HR for graft failure of 0.14 (95% confidence interval: 0.05-0.41), while patient survival was similar. Three other high-quality studies reported 5-year kidney graft survival rates of 48-89% for CLKT and 14-45% for KT. PLT and SLKT yielded 1-year patient and graft survival rates up to 100% in small cohorts.

CONCLUSIONS

Our study suggests that CLKT leads to superior kidney graft survival compared to KT. However, evidence for merits of SLKT or for KT in pyridoxine-responsive patients was scarce, which warrants further studies, ideally using data from a large international registry.

Combined liver kidney transplantation for primary hyperoxaluria type 1: Will there still be a future? Current transplantation strategies and monocentric experience

Combined liver-kidney transplantation is a therapeutic option for children affected by type 1 primary hyperoxaluria. Persistently high plasma oxalate levels may lead to kidney graft failure. It is debated whether pre-emptive liver transplantation, followed by kidney transplantation, might be a better strategy to reduce kidney graft loss. Our experience of 6 pediatric combined liver-kidney transplants for primary hyperoxaluria type 1 in pediatric recipients was retrospectively analyzed. Plasma oxalate levels were monitored before and after transplantation. All the recipients were on hemodialysis at transplantation. Median [IQR] recipient's age at transplantation was 11 [1-14] years; in all cases, a compatible graft from a pediatric brain-dead donor aged 8 [2-16] years was used. In a median follow-up of 7 [2-19] years after combined liver-kidney transplantation, no child died and no liver graft failure was observed; three kidney grafts were lost, due to chronic rejection, primary non-function, and early renal oxalate accumulation. Liver and kidney graft survival remained stable at 1, 3, and 5 years, at 100% and 85%, respectively. Kidney graft loss was the major complication in our series. Risk is higher with very young, low-weight donors. The impact of treatment with glyoxalate pathway enzyme inhibitors treatment in children with advanced disease as well as of donor kidney preservation by ex vivo machine perfusion needs to be evaluated. At present, a case-by-case discussion is needed to establish an optimal treatment strategy.

Primary hyperoxaluria type 1 in children: Clinical classification, renal replacement therapy, and outcome in a single centre experience

Primary hyperoxaluria type 1 (PH1) is a rare disease that is challenged by the overproduced oxalate and commonly presented with radiopaque renal stones or obstructive uropathy. This study aimed to report clinical presentations, renal replacement therapy (RRT), and outcome of PH1 in end stage kidney disease (ESKD) children. This is an observational cohort study. Data of 22 patients with ESKD due to PH1 were analyzed at Pediatric Nephrology Unit, Faculty of Medicine Cairo University. Infantile onset patients (n = 10) had worst renal outcome (80% with ESRD at presentation, p = 0.019) and worse patient outcome (mortality 40%, p = 0.016) than juvenile (n = 9) and late onset (PH1 n = 3) patients. RRT modalities include peritoneal dialysis (PD) in 7 (31.8%), hemodialysis (HD) in 11 (50%), and combined liver kidney transplantation (CLKT) in 4 (18.2%) patients. Infectious complications were encountered in 42.8% of PD patients. Better HD adequacy was observed with frequent HD (n = 6) and/or HD via arteriovenous fistula (AVF) than with infrequent dialysis (n = 5) and/or via central venous line (CVL) (p = 0.0001 and 0.0047, respectively). Morbidity and mortality (infection related) rates of the whole cohort were 63.6% and 31.8%, respectively. Clinical presentation of PH1 varies according to the age of onset (infantile onset being the most aggressive form). Aggressive HD (better through AVF) is needed to achieve acceptable HD adequacy, PD was challenged by infection. Infection found to be the main cause of mortality even after successful CLKT.

Living Related Liver Transplantation for Metabolic Liver Diseases in Children

ABSTRACT

Metabolic liver diseases (MLDs) are a heterogeneous group of inherited conditions for which liver transplantation can provide definitive treatment. The limited availability of deceased donor organs means some who could benefit from transplant do not have this option. Living related liver transplant (LrLT) using relatives as donors has emerged as one solution to this problem. This technique is established worldwide, especially in Asian countries, with shorter waiting times and patient and graft survival rates equivalent to deceased donor liver transplantation. However, living donors are underutilized for MLDs in many western countries, possibly due to the fear of limited efficacy using heterozygous donors. We have reviewed the published literature and shown that the use of heterozygous donors for liver transplantation is safe for the majority of MLDs with excellent metabolic correction. The use of LrLT should be encouraged to complement deceased donor liver transplantation (DDLT) for treatment of MLDs.

High-Capacity Adenoviral Vectors: Expanding the Scope of Gene Therapy

The adaptation of adenoviruses as gene delivery tools has resulted in the development of high-capacity adenoviral vectors (HC-AdVs), also known, helper-dependent or "gutless". Compared with earlier generations (E1/E3-deleted vectors), HC-AdVs retain relevant features such as genetic stability, remarkable efficacy of in vivo transduction, and production at high titers. More importantly, the lack of viral coding sequences in the genomes of HC-AdVs extends the cloning capacity up to 37 Kb, and allows long-term episomal persistence of transgenes in non-dividing cells. These properties open a wide repertoire of therapeutic opportunities in the fields of gene supplementation and gene correction, which have been explored at the preclinical level over the past two decades. During this time, production methods have been optimized to obtain the yield, purity, and reliability required for clinical implementation. Better understanding of inflammatory responses and the implementation of methods to control them have increased the safety of these vectors. We will review the most significant achievements that are turning an interesting research tool into a sound vector platform, which could contribute to overcome current limitations in the gene therapy field.

Liver Transplantation Outcome in Iranian Patients with Primary Hyperoxaluria; Risks and Perspectives

Background: Primary hyperoxaluria (PH) is an autosomal genetic disorder characterized by abnormal glycosylate metabolism. Objectives: The aim of the present study was to assess post-transplant complications and survival of patients with PH who underwent either liver transplantation (LT) or simultaneous liver-kidney transplantation. Methods: 18 patients with established PH diagnosis who underwent LT or simultaneous liver-kidney transplantation in the Transplantation Center of Shiraz, Iran, were included. Demographic and clinical data were collected by reviewing clinical documents and interviews by the patients. The patients were prospectively followed up for the occurrence of the intended outcomes. The data was analyzed by SPSS 18 software. Results: 12 patients (66.7%) were male, and six patients (33.3%) were female with the age range of 3 to 32 years (mean age, 18.89 ± 7.42 years). The patients’ weight ranged from 13 to 73 kg (mean weight, 47.39 ± 17.18 kg). Polyuria was the most common clinical presentation (11/18), and end-stage renal disease and hemodialysis were noted in 13 and 12 patients pre-transplantation, respectively. Hepatic arterial thrombosis, biliary complications, infections, and graft rejection comprised the most frequent post-transplant complications. Of 18 patients, seven patients (38.9%) died due to various complications during one year after transplant. Based on the Kaplan-Meier analysis, the survival rate was 61.1% at the end of the study. The mean survival time was 46.25 ± 18.6 months. The patients succumbed to the disease died within 3 to 320 days (mean, 61.57 days) post-surgery. Conclusions: LT seems an effective intervention in prevention of kidney failure in patients with PH.

Oxalobacter formigenes treatment combined with intensive dialysis lowers plasma oxalate and halts disease progression in a patient with severe infantile oxalosis

BACKGROUND

Infantile oxalosis, the most devastating form of primary hyperoxaluria type 1 (PH1), often leads to end-stage renal disease (ESRD) during the first weeks to months of life.

CASE-DIAGNOSIS

Here, we report the outcome of the therapeutic use of Oxalobacter formigenes (Oxabact OC5; OxThera AB, Stockholm, Sweden) in a female infant with PH1 who exhibited severely elevated plasma oxalate (Pox) levels, pronounced nephrocalcinosis, anuretic end-stage renal disease, and retinal oxalate deposits. Following the diagnosis of PH1 at an age of 8 weeks, a combined regimen of daily peritoneal dialysis, daily pyridoxine treatment and hemodialysis (3 times a week) was unable to reduce the pronounced hyperoxalemia. After the addition of Oxalobacter formigenes therapy to the otherwise unchanged treatment regimen, Pox levels first stabilized and subsequently declined from 130 μmol/L to around 80 μmol/L. Nephrocalcinosis and retinal deposits stabilized. Oxalobacter formigenes treatment was well-tolerated and no related adverse events were observed. The patient showed nearly age-appropriate growth and development and received successful combined liver-kidney transplantation at the age of two years.

CONCLUSIONS

Treatment with O. formigenes combined with intensive dialysis led to reduction of Pox, stabilization of systemic oxalosis, and improvement in the clinical disease course. O. formigenes treatment may be an option for reduction of oxalosis in infantile patients with insufficient response to conservative treatments until combined liver-kidney transplantation can be performed.

Oxalate retinopathy is irreversible despite early combined liver-kidney transplantation in primary hyperoxaluria type 1

In primary hyperoxaluria type 1 (PH1), systemic oxalate deposition (oxalosis) in end-stage renal disease (ESRD) is associated with high morbidity and mortality, particularly in children with infantile oxalosis (IO). Combined liver and kidney transplantation (CLKT) is the only curative treatment option in these patients. After CLKT, systemic oxalosis decreases continuously, although only insufficient data are available regarding oxalate retinopathy (ROx), leading to severe visual impairment. We analyzed long-term follow-up data of ROx in 13 patients undergoing CLKT for PH1 at our center between 1998 and 2018. Age at transplantation was 1.3-14.2 years, including nine patients with IO. We performed visual acuity testing, slit lamp investigation, funduscopy, fundus photography, and spectral-domain optical coherence tomography (SD-OCT) imaging. Severe (grade 2-4) ROx was present in all nine children with IO but not in the four patients developing ESRD in adolescence. A significant negative correlation was found between age at onset of ESRD and grade of ROx (r = -0.66; P < .001). Notably, follow-up assessment after CLKT demonstrated no regression of ROx after a median of 5.3 years (range 0.6-14). The data show that despite early CLKT in IO, ROx is irreversible and the concomitant visual deterioration occurs prior to transplantation.

Combined liver-kidney transplantation for primary hyperoxaluria type I in children: Single Center Experience

Primary hyperoxalurias are rare inborn errors of metabolism with deficiency of hepatic enzymes that lead to excessive urinary oxalate excretion and overproduction of oxalate which is deposited in various organs. Hyperoxaluria results in serious morbid-ity, end stage kidney disease (ESKD), and mortality if left untreated. Combined liver kidney transplantation (CLKT) is recognized as a management of ESKD for children with hyperoxaluria type 1 (PH1). This study aimed to report outcome of CLKT in a pediatric cohort of PH1 patients, through retrospective analysis of data of 8 children (2 girls and 6 boys) who presented by PH1 to Wadi El Nil Pediatric Living Related Liver Transplant Unit during 2001-2017. Mean age at transplant was 8.2 ± 4 years. Only three of the children underwent confirmatory genotyping. Three patients died prior to surgery on waiting list. The first attempt at CLKT was consecutive, and despite initial successful liver transplant, the girl died of biliary peritonitis prior to scheduled renal transplant. Of the four who underwent simultaneous CLKT, only two survived and are well, one with insignificant complications, and other suffered from abdominal Burkitt lymphoma managed by excision and resection anastomosis, four cycles of rituximab, cyclophosphamide, vincristine, and prednisone. The other two died, one due to uncontrollable bleeding within 36 hours of procedure, while the other died awaiting renal transplant after loss of renal graft to recurrent renal oxalosis 6 months post-transplant. PH1 with ESKD is a rare disease; simultaneous CLKT offers good quality of life for afflicted children. Graft shortage and renal graft loss to oxalosis challenge the outcome.

Bilateral native nephrectomy to reduce oxalate stores in children at the time of combined liver-kidney transplantation for primary hyperoxaluria type 1

OBJECTIVE

Primary hyperoxaluria type-1 (PH-1) is a rare genetic disorder in which normal hepatic metabolism of glyoxylate is disrupted resulting in diffuse oxalate deposition and end-stage renal disease (ESRD). While most centers agree that combined liver-kidney transplant (CLKT) is the appropriate treatment for PH-1, perioperative strategies for minimizing recurrent oxalate-related injury to the transplanted kidney remain unclear. We present our management of children with PH-1 and ESRD on hemodialysis (HD) who underwent CLKT at our institution from 2005 to 2015.

METHODS

On chart review, three patients (2 girls, 1 boy) met study criteria. Two patients received deceased-donor split-liver grafts, while one patient received a whole liver graft. All patients underwent bilateral native nephrectomy at transplant to minimize the total body oxalate load. Median preoperative serum oxalate was 72 μmol/L (range 17.8-100). All patients received HD postoperatively until predialysis serum oxalate levels fell <20 μmol/L. All patients, at a median of 7.5 years of follow-up (range 6.5-8.9), demonstrated stable liver and kidney function.

CONCLUSIONS

While CLKT remains the definitive treatment for PH-1, bilateral native nephrectomy at the time of transplant reduces postoperative oxalate stores and may mitigate damage to the renal allograft.

Calcified Double J Stent after Sequential Liver and Renal Transplantation Associated to Primary Oxalosis: Case Report

Hyperoxaluria type I (HPI) is a metabolic disorder secondary to liver alanine glyoxylate aminotransferase deficiency. Renal failure occurs due to the excessive production and precipitation of oxalate in the kidney. Combined liver-renal transplantation is the correct treatment for this condition when end-stage renal failure occurs since in renal transplantation alone the risk of recurrence of the same pathology in the transplanted kidney would be high.

We determined the calcification surrounding the double J stent inserted to the transplant ureter in a short time in a 22-year-old patient who underwent sequential liver and renal transplantation with the diagnoses of oxalosis. In the literature we have not found papers on calcification of double J stent following combined or sequential transplantation. Although after the sequential transplantation the calcification, nephrocalcinosis, and renal stones were practically not of great concern, these patients should be followed up more carefully in terms of stent calcification during the early post-transplant period.

An institutional experience of pre-emptive liver transplantation for pediatric primary hyperoxaluria type 1

Primary hyperoxaluria type 1 (PH1) is an inherited metabolic disease that culminates in ESRF. Pre-emptive liver transplantation (pLTx) treats the metabolic defect and avoids the need for kidney transplantation (KTx). An institutional experience of pediatric PH1 LTx is reported and compared to the literature. Between 2004 and 2015, eight children underwent pLTx for PH1. Three underwent pLTx with a median GFR of 40 (30-46) mL/min/1.73 m(2) and five underwent sequential combined liver-kidney transplantation (cLKTx); all were on RRT at the time of cLKTx. In one case of pLTx, KTx was required eight and a half yr later. pLTx was performed in older (median 8 vs. 2 yr) and larger children (median 27 vs. 7.75 kg) that had a milder PH1 phenotype. In pediatric PH1, pLTx, ideally, should be performed before renal and extrarenal systemic oxalosis complications have occurred, and pLTx can be used "early" or "late." Early is when renal function is preserved with the aim to avoid renal replacement. However, in late (GFR < 30 mL/min/1.73 m(2) ), the aim is to stabilize renal function and delay the need for KTx. Ultimately, transplant strategy depends on PH1 phenotype, disease stage, child size, and organ availability.

Review of combined liver and kidney transplantation in children

In this review, we focused on CLKT with regard to indication, results, outcome, and future developments. PH1 is one of the most common diagnoses for adult and pediatric patients qualifying for CLKT. The other major indication for combined transplantation is ARPKD. CLKT appears to be superior to sequential liver and kidney transplantation in the majority of patients and overall results following CLKT are now good, even in small children. Clinical observations suggest that there is an immunological advantage of CLKT in comparison with isolated liver or kidney transplantation. More clinical studies are necessary to identify the best candidates for CLKT while the availability of donor organs is low.

Primary and secondary hyperoxaluria: Understanding the enigma

Hyperoxaluria is characterized by an increased urinary excretion of oxalate. Primary and secondary hyperoxaluria are two distinct clinical expressions of hyperoxaluria. Primary hyperoxaluria is an inherited error of metabolism due to defective enzyme activity. In contrast, secondary hyperoxaluria is caused by increased dietary ingestion of oxalate, precursors of oxalate or alteration in intestinal microflora. The disease spectrum extends from recurrent kidney stones, nephrocalcinosis and urinary tract infections to chronic kidney disease and end stage renal disease. When calcium oxalate burden exceeds the renal excretory ability, calcium oxalate starts to deposit in various organ systems in a process called systemic oxalosis. Increased urinary oxalate levels help to make the diagnosis while plasma oxalate levels are likely to be more accurate when patients develop chronic kidney disease. Definitive diagnosis of primary hyperoxaluria is achieved by genetic studies and if genetic studies prove inconclusive, liver biopsy is undertaken to establish diagnosis. Diagnostic clues pointing towards secondary hyperoxaluria are a supportive dietary history and tests to detect increased intestinal absorption of oxalate. Conservative treatment for both types of hyperoxaluria includes vigorous hydration and crystallization inhibitors to decrease calcium oxalate precipitation. Pyridoxine is also found to be helpful in approximately 30% patients with primary hyperoxaluria type 1. Liver-kidney and isolated kidney transplantation are the treatment of choice in primary hyperoxaluria type 1 and type 2 respectively. Data is scarce on role of transplantation in primary hyperoxaluria type 3 where there are no reports of end stage renal disease so far. There are ongoing investigations into newer modalities of diagnosis and treatment of hyperoxaluria. Clinical differentiation between primary and secondary hyperoxaluria and further between the types of primary hyperoxaluria is very important because of implications in treatment and diagnosis. Hyperoxaluria continues to be a challenging disease and a high index of clinical suspicion is often the first step on the path to accurate diagnosis and management.

Primary disease recurrence—effects on paediatric renal transplantation outcomes

Primary disease recurrence after renal transplantation is mainly diagnosed by examination of biopsy samples, but can also be associated with clinical symptoms. In some patients, recurrence can lead to graft loss (7-8% of all graft losses). Primary disease recurrence is generally associated with a high risk of graft loss in patients with focal segmental glomerulosclerosis, membranous proliferative glomerulonephritis, primary hyperoxaluria or atypical haemolytic uraemic syndrome. By contrast, disease recurrence is associated with a limited risk of graft loss in patients with IgA nephropathy, renal involvement associated with Henoch-Schönlein purpura, antineutrophil cytoplasmic antibody-associated glomerulonephritis or lupus nephritis. The presence of systemic diseases that affect the kidneys, such as sickle cell anaemia and diabetes mellitus, also increases the risk of delayed graft loss. This Review provides an overview of the epidemiology, pathophysiology and management of primary disease recurrence in paediatric renal graft recipients, and describes the overall effect on graft survival of each of the primary diseases listed above. With appropriate management, few paediatric patients should be excluded from renal transplantation programmes because of an increased risk of recurrence.

Two-step transplantation for primary hyperoxaluria: a winning strategy to prevent progression of systemic oxalosis in early onset renal insufficiency cases

Several transplant strategies for PH1 have been proposed, and LT is performed to correct the metabolic defects. The patients with PH1 often suffer from ESRD and require simultaneous LKT, which leads to a long wait due to the shortage of suitable organ donors. Five patients with PH1 underwent LDLT at our institute. Three of the five patients were under dialysis before LDLT, while the other two patients were categorized as CKD stage 3. An isolated LDLT was successfully performed in all but our first case, who had complicated postoperative courses and consequently died due to sepsis after retransplantation. The renal function of the patients with CKD stage 3 was preserved after LDLT. On the other hand, our second case with ESRD underwent successful LDKT six months after LDLT, and our infant case is waiting for the subsequent KT without any post-LDLT complications after the early establishment of PD. In conclusion, a two-step transplant strategy may be needed as a life-saving option for patients with PH1 and may be possible even in small infants with systemic oxalosis. While waiting for a subsequent KT, an early resumption of PD should be considered from the perspective of the long-term requirement of RRT.

Combined liver and kidney transplantation in children

Simultaneous combined liver-kidney transplantation (CLKT) is a rare operation in pediatric patients so that annually only 10-30 operations are performed worldwide. The main indications for CLKT are primary hyperoxaluria type 1 and autosomal recessive polycystic kidney disease. In addition, CLKT is indicated in individual patients with metabolic or cirrhotic liver diseases and end-stage kidney disease. The surgery and immediate post-operative management of CLKT remain challenging in infants and small children. The patients should be operated on before they become severely ill or develop major systemic manifestations of their metabolic disorder. The liver allograft is immunologically protective of the kidney graft in simultaneous CLKT, often resulting in well-preserved kidney function. The long-term outcome after CLKT is nowadays comparable to that of isolated liver and kidney transplantations.

Primary hyperoxaluria type 1: practical and ethical issues

Primary hyperoxaluria type 1 (PH1) is a rare inborn error of glyoxylate metabolism of autosomal recessive inheritance, leading to progressive systemic oxalate storage (named 'oxalosis') with a high rate of morbidity and mortality, as well as an unacceptable quality of life for most patients. The adverse outcome, however, is partly due to issues that can be overcome. First, the diagnosis of PH is often delayed due to a general lack of knowledge of the disease among physicians. This accounts specifically for patients with pyridoxine sensitive PH, a group that is paradoxically most easy to treat. Second, lack of adherence to a strict conduction of conservative treatment and optimal urological management may enhance an adverse outcome of the disease. Third, specific techniques to establish PH1 and specific therapies are currently often not available in several low-resources countries with a high prevalence of PH. The management of patients with advanced disease is extremely difficult and warrants a tailor-made approach in most cases. Comprehensive programs for education of local physicians, installation of national centers of expertise, European support of low-resources countries for the management of PH patients and intensified international collaboration on the management of current patients, as well as on conduction of clinical studies, may further improve outcome of PH.

Combined liver-kidney transplantation for children with autosomal recessive polycystic kidney disease (ARPKD): indication and outcome

In ARPKD, mutations in the PKHD1 gene lead to remodeling of the kidneys and liver. These may result in progressive liver fibrosis with portal hypertension requiring combined liver and kidney transplantation (CLKT). There is currently no consensus on the indication for CLKT and data on long-term outcomes are scarce. We analyzed in detail the pretransplant liver symptomatology, laboratory and ultrasound data, histological studies, and genotypes in eight patients undergoing CLKT. The median age was 10.1 years (range 1.7-16) and median follow-up was 4.6 years (range 1.1-8.9). All patients had clinical signs of portal hypertension and abnormal ultrasound findings. Congenital hepatic fibrosis was present in all pretransplant biopsies (6 out of 8 patients) and in all explanted livers. All patients survived; liver and kidney graft survival was 72% and 88%, respectively. Liver and kidney function were stable in all patients with a median eGFR of 70 ml/min/1.73 m² (range 45-108 ml/min/1.73 m²). Height-SDS improved significantly after 12, 24, and 36 months (P = 0.016, 0.022 and 0.018 respectively). The indication for CLKT remains challenging and controversial. A favorable outcome for patients with ARPKD can be achieved by using the degree of portal hypertension, longitudinal ultrasound examinations, and preoperative liver histology as parameters for CLKT.

Conservative treatment of a pathological fracture in a 3-year-old boy with primary hyperoxaluria type I

Primary hyperoxaluria type I is a rare inherited disease that presents a disturbed metabolism of glyoxylate. Consequently, patients suffer from hyperoxaluria, leading to renal failure and subsequent skeletal calcium oxalate deposition. Areas with high concentrations of calcium oxalate, so-called dense metaphyseal bands, are at risk for pathological fracturing. The primary disease is treated by combined liver-kidney transplantation, although pathological fracturing also occurs in the posttransplant period. In the current case, we present a 3-year-old boy with a pathological fracture of his right femur, 2 years after liver-kidney transplantation. We opted for a conservative regime, leading to good fracture healing. As there are limited data in the literature regarding treatment of fractures in these patients, it is important to notify the outcome of conservative treatment of pathological fractures in patients with primary hyperoxaluria type I.

Liver transplantation for primary hyperoxaluria type 1: a single-center experience during two decades in Japan

BACKGROUND

Primary hyperoxaluria type-1 (PH1) is an autosomal recessive disorder caused by impaired activity of hepatic peroxisomal alanine-glyoxylate aminotransferase that leads to end-stage renal disease (ESRD). A definitive diagnosis is often delayed until ESRD appears. Based on the etiology, liver transplantation (LT) seems to be the definitive treatment.

PATIENTS AND METHODS

Three PH1 patients underwent LT at our institution during two decades.

RESULTS

Two of the patients had family histories of cryptogenic ESRD. All three showed disease onset in childhood, but the definitive diagnosis was delayed in two cases (17 and 37 years of age). These delayed cases resulted in ESRD, and hemodialysis (HD) had been introduced before LT. One patient received domino LT, and the other two underwent living-donor LT (LDLT). One patient finally died of sepsis, and was unable to receive a kidney transplantation (KT) after the domino LT. One patient did not show ESRD, and did not have to undergo KT after LDLT, although extracorporeal shock wave lithotripsy was required for residual ureterolithiasis (8 years after LDLT). The third patient had an uneventful course after LDLT and received living-donor KT from the same donor 8 months after LDLT. Subsequently, HD was successfully withdrawn.

CONCLUSIONS

Establishment of a definitive diagnosis of PH1 is essential. If a methodology for early diagnosis and an intensive care strategy for neonates and infants during the waiting time become well-established, a timely and preemptive LT alone can provide a good chance of cure for PH1 patients.

Primary hyperoxaluria Type 1: indications for screening and guidance for diagnosis and treatment

Primary hyperoxaluria Type 1 is a rare autosomal recessive inborn error of glyoxylate metabolism, caused by a deficiency of the liver-specific enzyme alanine:glyoxylate aminotransferase. The disorder results in overproduction and excessive urinary excretion of oxalate, causing recurrent urolithiasis and nephrocalcinosis. As glomerular filtration rate declines due to progressive renal involvement, oxalate accumulates leading to systemic oxalosis. The diagnosis is based on clinical and sonographic findings, urine oxalate assessment, enzymology and/or DNA analysis. Early initiation of conservative treatment (high fluid intake, pyridoxine, inhibitors of calcium oxalate crystallization) aims at maintaining renal function. In chronic kidney disease Stages 4 and 5, the best outcomes to date were achieved with combined liver-kidney transplantation.

Hyperoxaluria and systemic oxalosis: an update on current therapy and future directions

INTRODUCTION

The primary hyperoxalurias (PH) are rare, but underdiagnosed disorders where the loss of enzymatic activity in key compounds of glyoxylate metabolism results in excessive endogenous oxalate generation. Clinically, they are characterized by recurrent urolithiasis and/or nephrocalcinosis. PH type I is the most frequent and most devastating subtype often leading to early end-stage renal failure.

AREAS COVERED

Profound overview of clinical, diagnostic, and currently available treatment options with a focus on PH I at different stages of the disease. Discussion of future therapeutic avenues including pharmacological chaperones (small molecules rescuing protein function), gene therapy with safer adenoviral vectors, and potential application of cell-based transplantation strategies is provided.

EXPERT OPINION

Due to lack of familiarity with PH and its heterogeneous clinical expression, diagnosis is often delayed until advanced disease is present, a condition, requiring intensive hemodialysis and timely transplantation. Achieving the most beneficial outcome largely depends on the knowledge of the clinical spectrum, early diagnosis, and initiation of treatment before renal failure ensues. A number of preconditions required for substantial improvement in the care of orphan disease like PH have now been achieved or soon will come within reach, so new treatment options can be expected in the near future.

Novel findings in patients with primary hyperoxaluria type III and implications for advanced molecular testing strategies

Identification of mutations in the HOGA1 gene as the cause of autosomal recessive primary hyperoxaluria (PH) type III has revitalized research in the field of PH and related stone disease. In contrast to the well-characterized entities of PH type I and type II, the pathophysiology and prevalence of type III is largely unknown. In this study, we analyzed a large cohort of subjects previously tested negative for type I/II by complete HOGA1 sequencing. Seven distinct mutations, among them four novel, were found in 15 patients. In patients of non-consanguineous European descent the previously reported c.700+5G>T splice-site mutation was predominant and represents a potential founder mutation, while in consanguineous families private homozygous mutations were identified throughout the gene. Furthermore, we identified a family where a homozygous mutation in HOGA1 (p.P190L) segregated in two siblings with an additional AGXT mutation (p.D201E). The two girls exhibiting triallelic inheritance presented a more severe phenotype than their only mildly affected p.P190L homozygous father. In silico analysis of five mutations reveals that HOGA1 deficiency is causing type III, yet reduced HOGA1 expression or aberrant subcellular protein targeting is unlikely to be the responsible pathomechanism. Our results strongly suggest HOGA1 as a major cause of PH, indicate a greater genetic heterogeneity of hyperoxaluria, and point to a favorable outcome of type III in the context of PH despite incomplete or absent biochemical remission. Multiallelic inheritance could have implications for genetic testing strategies and might represent an unrecognized mechanism for phenotype variability in PH.

An update on primary hyperoxaluria

The autosomal recessive inherited primary hyperoxalurias types I, II and III are caused by defects in glyoxylate metabolism that lead to the endogenous overproduction of oxalate. Type III primary hyperoxaluria was first described in 2010 and further types are likely to exist. In all forms, urinary excretion of oxalate is strongly elevated (>1 mmol/1.73 m(2) body surface area per day; normal <0.5 mmol/1.73 m(2) body surface area per day), which results in recurrent urolithiasis and/or progressive nephrocalcinosis. All entities can induce kidney damage, which is followed by reduced oxalate elimination and consequent systemic deposition of calcium oxalate crystals. Systemic oxalosis should be prevented, but diagnosis is all too often missed or delayed until end-stage renal disease (ESRD) occurs; this outcome occurs in >30% of patients with primary hyperoxaluria type I. The fact that such a large proportion of patients have such poor outcomes is particularly unfortunate as ESRD can be delayed or even prevented by early intervention. Treatment options for primary hyperoxaluria include alkaline citrate, orthophosphate, or magnesium. In addition, pyridoxine treatment can be used to normalize or reduce oxalate excretion in about 30% of patients with primary hyperoxaluria type I. Time on dialysis should be short to avoid overt systemic oxalosis. Transplantation methods depend on the type of primary hyperoxaluria and on the particular patient, but combined liver and kidney transplantation is the method of choice in patients with primary hyperoxaluria type I and isolated kidney transplantation is the preferred method in those with primary hyperoxaluria type II. To the best of our knowledge, progression to ESRD has not yet been reported in any patient with primary hyperoxaluria type III.

Primary hyperoxalurias: disorders of glyoxylate detoxification

Glyoxylate detoxification is an important function of human peroxisomes. Glyoxylate is a highly reactive molecule, generated in the intermediary metabolism of glycine, hydroxyproline and glycolate mainly. Glyoxylate accumulation in the cytosol is readily transformed by lactate dehydrogenase into oxalate, a dicarboxylic acid that cannot be metabolized by mammals and forms tissue-damaging calcium oxalate crystals. Alanine-glyoxylate aminotransferase, a peroxisomal enzyme in humans, converts glyoxylate into glycine, playing a central role in glyoxylate detoxification. Cytosolic and mitochondrial glyoxylate reductase also contributes to limit oxalate production from glyoxylate. Mitochondrial hydroxyoxoglutarate aldolase is an important enzyme of hydroxyproline metabolism. Genetic defect of any of these enzymes of glyoxylate metabolism results in primary hyperoxalurias, severe human diseases in which toxic levels of oxalate are produced by the liver, resulting in progressive renal damage. Significant advances in the pathophysiology of primary hyperoxalurias have led to better diagnosis and treatment of these patients, but current treatment relies mainly on organ transplantation. It is reasonable to expect that recent advances in the understanding of the molecular mechanisms of disease will result into better targeted therapeutic options in the future.

An unexpected cause of progressive renal failure in a 66-year-old male after liver transplantation: secondary hyperoxaluria

BACKGROUND

Hyperoxaluria is a rare metabolic disorder characterized by calcium oxalate deposition in different tissues. It is caused either by an inherited disease of oxalate metabolism [primary hyperoxalurias (PH)] or by an acquired disturbance (secondary hyperoxaluria).

CASE

We report here an atypical presentation of enteric hyperoxaluria-induced renal failure that occurred after liver transplantation. Despite adapted treatment and intensive haemodialysis, the patient did not recover. This case allows the reviewing of the multiple pathophysiological mechanisms involved in this disease.

CONCLUSION

Oxalate nephropathy should be considered in the differential diagnosis of acute renal failure, especially when previous renal impairment and fat malabsorption are present. We suggest performing renal biopsy early to allow a prompt diagnosis and therapeutic intervention.

Liver cell transplantation in severe infantile oxalosis--a potential bridging procedure to orthotopic liver transplantation?

BACKGROUND

The infantile form of primary hyperoxaluria type I (PHI) is the most devastating PH subtype leading to early end-stage renal failure and severe systemic oxalosis. Combined or sequential liver-kidney transplantation (LKTx) is the only curative option but it involves substantial risks, especially in critically ill infants. The procedure also requires resources that are simply not available to many children suffering from PHI worldwide. Less invasive and less complex therapeutic interventions allowing a better timing are clearly needed. Liver cell transplantation (LCT) may expand the narrow spectrum of auxiliary measures to buy time until LKTx for infants can be performed more safely.

METHODS

We performed LCT (male neonate donor) in a 15-month-old female in reduced general condition suffering from systemic oxalosis. Renal replacement therapy, initiated at the age of 3 months, was complicated by continuous haemodialysis access problems. Living donor liver transplantation was not available for this patient. Plasma oxalate (Pox) was used as the primary outcome measure.

RESULTS

Pox decreased from 104.3±8.4 prior to 70.0±15.0 μmol/L from Day 14 to Day 56 after LCT. A significant persistent Pox reduction (P<0.001) comparing mean levels prior to (103.8 μmol/L) and after Day 14 of LCT until LKTx (77.3 μmol/L) was seen, although a secondary increase and wider range of Pox was also observed. In parallel, the patient's clinical situation markedly improved and the girl received a cadaveric LKTx 12 months after LCT. However, biopsy specimens taken from the explanted liver did not show male donor cells by amelogenin polymerase chain reaction.

CONCLUSIONS

With due caution, our pilot data indicate that LCT in infantile oxalosis warrants further investigation. Improvement of protocol and methodology is clearly needed in order to develop a procedure that could assist in the cure of PHI.

Characteristics and outcomes of children with primary oxalosis requiring renal replacement therapy

BACKGROUND AND OBJECTIVES

Primary hyperoxaluria (PH) as a cause of ESRD in children is believed to have poor outcomes. Data on management and outcomes of these children remain scarce.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study included patients aged <19 years who started renal replacement therapy (RRT) between 1979 and 2009 from 31 countries providing data to a large European registry.

RESULTS

Of 9247 incident patients receiving RRT, 100 patients had PH. PH children were significantly younger than non-PH children at the start of RRT. The median age at RRT of PH children decreased from 9.8 years in 1979-1989 to 1.5 years in 2000-2009. Survival was 86%, 79%, and 76% among PH patients at 1, 3, and 5 years after the start of RRT, compared with 97%, 94%, and 92% in non-PH patients, resulting in a three-fold increased risk of death over non-PH patients. PH and non-PH patient survival improved over time. Sixty-eight PH children received a first kidney (n=13) or liver-kidney transplantation (n=55). Although the comparison was hampered by the lower number of kidney transplantations primarily derived from the earlier era of RRT, kidney graft survival in PH patients was 82%, 79%, and 76% at 1, 3, and 5 years for liver-kidney transplantation and 46%, 28%, and 14% at 1, 3, and 5 years for kidney transplantation alone, compared with 95%, 90%, and 85% in non-PH patients.

CONCLUSIONS

The outcomes of PH children with ESRD are still poorer than in non-PH children but have substantially improved over time.

Characteristics and outcomes of children with primary oxalosis requiring renal replacement therapy

BACKGROUND AND OBJECTIVES

Primary hyperoxaluria (PH) as a cause of ESRD in children is believed to have poor outcomes. Data on management and outcomes of these children remain scarce.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study included patients aged <19 years who started renal replacement therapy (RRT) between 1979 and 2009 from 31 countries providing data to a large European registry.

RESULTS

Of 9247 incident patients receiving RRT, 100 patients had PH. PH children were significantly younger than non-PH children at the start of RRT. The median age at RRT of PH children decreased from 9.8 years in 1979-1989 to 1.5 years in 2000-2009. Survival was 86%, 79%, and 76% among PH patients at 1, 3, and 5 years after the start of RRT, compared with 97%, 94%, and 92% in non-PH patients, resulting in a three-fold increased risk of death over non-PH patients. PH and non-PH patient survival improved over time. Sixty-eight PH children received a first kidney (n=13) or liver-kidney transplantation (n=55). Although the comparison was hampered by the lower number of kidney transplantations primarily derived from the earlier era of RRT, kidney graft survival in PH patients was 82%, 79%, and 76% at 1, 3, and 5 years for liver-kidney transplantation and 46%, 28%, and 14% at 1, 3, and 5 years for kidney transplantation alone, compared with 95%, 90%, and 85% in non-PH patients.

CONCLUSIONS

The outcomes of PH children with ESRD are still poorer than in non-PH children but have substantially improved over time.

Hyperoxaluria and rapid development of renal failure following a combined liver and kidney transplantation: emphasis on sequential transplantation

Primary hyperoxaluria type I (PH I) is a rare genetic disorder that leads to end stage renal disease (ESRD) at an early age due to excessive deposition of calcium oxalate in the kidney. Combined liver-kidney transplantation (LKTx) has been advocated as the treatment of choice for patients with PH I who have progressive renal disease. With combined LKTx the risk of early renal failure secondary to oxalate deposition is anticipated. Here we report a patient with PH I who developed ESRD and underwent a combined LKTx. He lost the kidney graft secondary to early recurrence of oxalosis. Repeat kidney transplantation 13 months after the initial procedure was successful. Elevated plasma oxalate levels persisted for a long time following LKTx and lead to further deposition of oxalate in the second kidney graft. Combined LKTx for patients with PH I requires meticulous preparation and very careful post operative management. Sequential liver transplantation followed by kidney transplantation is to be considered for PH I patients who have ESRD and very high oxalate load.

Primary hyperoxaluria

Primary hyperoxalurias (PH) are inborn errors in the metabolism of glyoxylate and oxalate. PH type 1, the most common form, is an autosomal recessive disorder caused by a deficiency of the liver-specific enzyme alanine, glyoxylate aminotransferase (AGT) resulting in overproduction and excessive urinary excretion of oxalate. Recurrent urolithiasis and nephrocalcinosis are the hallmarks of the disease. As glomerular filtration rate decreases due to progressive renal damage, oxalate accumulates leading to systemic oxalosis. Diagnosis is often delayed and is based on clinical and sonographic findings, urinary oxalate assessment, DNA analysis, and, if necessary, direct AGT activity measurement in liver biopsy tissue. Early initiation of conservative treatment, including high fluid intake, inhibitors of calcium oxalate crystallization, and pyridoxine in responsive cases, can help to maintain renal function in compliant subjects. In end-stage renal disease patients, the best outcomes have been achieved with combined liver-kidney transplantation which corrects the enzyme defect.

Surgical aspects and outcome of combined liver and kidney transplantation in children

In children with renal insufficiency and accompanying or underlying liver disease, combined liver and kidney transplantations (CLKT) are indicated. However, because of the rare indications, the number of paediatric CLKT is low. Our aim was to analyse CLKT in children with special regard to surgical aspects and outcome. All paediatric CLKT performed at our institution between 1998 and 2009 were retrospectively analysed. Between 1998 and 2009, 15 CLKT were performed in 14 paediatric patients (median age 8 years, range 1-16 years). The indications for CLKT were autosomal recessive polycystic kidney disease (n = 7), primary hyperoxaluria type 1 (n = 7) and retransplantation because of primary liver nonfunction (n = 1). In the postoperative course, six patients showed bleeding complications, thereof three patients needed operative revision for intra-abdominal bleeding. Eight of 15 patients (53%) needed dialysis. The 1- and 5-year patient survival was 100%; and 1- and 5-year graft survival was 80% for the liver and 93% for the kidney allograft. A number of different complications, especially secondary haemorrhage have to be anticipated after CLKT, requiring a timely and interdisciplinary treatment approach. With this management, our patients showed an excellent graft and patient survival.

Liver transplantation in oxalosis prior to advanced chronic kidney disease

While curative of the disease, combined kidney and liver transplantation (K/LTx) for primary hyperoxaluria type 1 (PH1) continues to carry with it a risk for patient death of 15-25%, which over time may not differ from that of kidney transplantation alone (KTx). In this editorial, survival data are reviewed as well as the limited data available for kidney graft function, which may favor K/LTx in the short term but is more uncertain in the longer term. The window of opportunity that favors preemptive K/LTx is relatively narrow and is likely even narrower for preemptive isolated LTx. Capability and experience in the medical management of such patients, and the opportunities available, as well as likely patient compliance, so far without supporting data, may be the most important determination of the best strategy for management.

Excellent renal function and reversal of nephrocalcinosis 8 years after isolated liver transplantation in an infant with primary hyperoxaluria type 1

Primary hyperoxaluria type 1 (PH-1) is a rare autosomal recessive disease caused by the absence or deficiency of the liver-specific intermediary metabolic enzyme alanine glyoxylate aminotransferase. The prognosis of this metabolic disease is poor. Theoretically, the primary metabolic defect can be cured by liver transplantation. However, controversy exists around the age and stage of the disease that liver transplantation should be performed. We report on a patient who presented at the early age of 2 months with nephrocalcinosis. Isolated liver transplantation was performed at the age of 21 months. Eight years later, the estimated glomerular filtration rate was 85 ml/min/1.73 m(2), and imaging studies did not reveal nephrocalcinosis. This case report supports the strategy of early isolated liver transplantation in patients with PH-1.

Liver transplantation for inherited metabolic disorders of the liver

PURPOSE OF REVIEW

Liver transplantation is curative, life saving or both for a range of inherited diseases affecting the liver. Indications, timing and outcome of transplantation for these diseases are the focus of this review.

RECENT FINDINGS

Liver transplant represents a mode of gene replacement therapy for several disorders, including Wilson disease, hemochromatosis, tyrosinemia, urea cycle defects and hypercholesterolemia in which the primary defect residing in the liver results in hepatic complications or severe extrahepatic disease. Liver transplant is also an important therapeutic modality in multisystemic genetic disorders with major hepatic disease such as glycogen storage disease types I, III and IV and porphyria. For familial amyloidosis and primary hyperoxaluria, liver replacement eliminates the source of the injurious products that results in extrahepatic disease. Innovations in medical and surgical management of these patients have led to improved outcomes providing an important benchmark for future gene therapy of these disorders.

SUMMARY

Recent developments have refined the indications for liver transplant in the treatment of inherited metabolic diseases. The full potential of liver transplant in these disorders can be harnessed by careful patient selection, optimizing timing and perioperative metabolic management of these patients.

Pre-emptive liver transplantation for primary hyperoxaluria (PH-I) arrests long-term renal function deterioration

BACKGROUND

Primary hyperoxaluria-I (PH-I) is a serious metabolic disease resulting in end-stage renal disease. Pre-emptive liver transplantation (PLT) for PH-I is an option for children with early diagnosis. There is still little information on its effect on long-term renal function in this situation.

METHODS

Long-term assessment of renal function was conducted using Schwartz's formula (estimated glomerular filtration rate-eGFR) in four children (Group A) undergoing PLT between 2002 and 2008, and a comparison was done with eight gender- and sex-matched controls (Group B) having liver transplantation for other indications.

RESULTS

All patients received a liver graft from a deceased donor. Median follow-up for the two groups was 64 and 94 months, respectively. One child in Group A underwent re-transplantation due to hepatic artery thrombosis, while acute rejection was seen in one. A significant difference was seen in eGFR at transplant (81 vs 148 mL/min/1.73 m(2)) with greater functional impairment seen in the study population. In Group A, renal function reduced by 21 and 11% compared with 37 and 35% in Group B at 12 and 24 months, respectively. At 2 years post-transplantation, there was no significant difference in eGFR between the two groups (72 vs 100 mL/min/1.73 m(2), respectively; P = 0.06).

CONCLUSIONS

Renal function remains relatively stable following pre-emptive LTx for PH-I. With early diagnosis of PH-I, isolated liver transplantation may prevent progression to end-stage renal disease and the need for renal transplantation.