Orthotopic liver transplantation for Crigler-Najjar type I disease in six children

Human liver stem/progenitor cells decrease serum bilirubin in hyperbilirubinemic Gunn rat

AIM: To test the ability of adult-derived human liver stem/progenitor cells (ADHLSC) from large scale cultures to conjugate bilirubin in vitro and in bilirubin conjugation deficient rat.

METHODS: ADHLSC from large scale cultures were tested for their phenotype and for their capacity to conjugate bilirubin in vitro after hepatogenic differentiation. In vivo, Gunn rats [uridine diphosphate-glucuronosyltransferase 1A1 (UGT1A1) deficient animal] were injected with ADHLSC and cryopreserved hepatocytes (positive control). Two, 4, 13 and 27 wk post-transplantation, transplanted Gunn rat bilirubin serum levels were determined by high performance liquid chromatography. Human transplanted cell engraftment was assessed 27 wk post-transplantation using immunohistochemistry and RTqPCR.

RESULTS: Large scale culture conditions do not modify ADHLSC phenotype, ADHLSC were able to specifically conjugate bilirubin. ADHLSC were intraportally injected into Gunn rats and blood UCB was measured at different times post-transplantation, infused-Gunn rats exhibited a metabolic effect 3 mo post-transplantation and maintained over a 6 mo period. ADHLSC engraftment into Gunn rat’s liver was demonstrated by RTqPCR and immunohistochemistry against albumin and UGT1A1.

CONCLUSION: ADHLSC from large scale cultures are efficient in conjugating bilirubin in vitro and in restoring a deficient metabolic function (reducing bilirubin level) in hyperbilirubinemic rats.

Monogenic diseases that can be cured by liver transplantation

While the prevalence of most diseases caused by single-gene mutations is low and defines them as rare conditions, all together, monogenic diseases account for approximately 10 in every 1000 births according to the World Health Organisation. Orthotopic liver transplantation (LT) could offer a therapeutic option in monogenic diseases in two ways: by substituting for an injured liver or by supplying a tissue that can replace a mutant protein. In this respect, LT may be regarded as the correction of a disease at the level of the dysfunctional protein. Monogenic diseases that involve the liver represent a heterogeneous group of disorders. In conditions associated with predominant liver parenchymal damage (i.e., genetic cholestatic disorders, Wilson's disease, hereditary hemochromatosis, tyrosinemia, α1 antitrypsin deficiency), hepatic complications are the major source of morbidity and LT not only replaces a dysfunctional liver but also corrects the genetic defect and effectively cures the disease. A second group includes liver-based genetic disorders characterised by an architecturally near-normal liver (urea cycle disorders, Crigler-Najjar syndrome, familial amyloid polyneuropathy, primary hyperoxaluria type 1, atypical haemolytic uremic syndrome-1). In these defects, extrahepatic complications are the main source of morbidity and mortality while liver function is relatively preserved. Combined transplantation of other organs may be required, and other surgical techniques, such as domino and auxiliary liver transplantation, have been attempted. In a third group of monogenic diseases, the underlying genetic defect is expressed at a systemic level and liver involvement is just one of the clinical manifestations. In these conditions, LT might only be partially curative since the abnormal phenotype is maintained by extrahepatic synthesis of the toxic metabolites (i.e., methylmalonic acidemia, propionic acidemia). This review focuses on principles of diagnosis, management and LT results in both paediatric and adult populations of selected liver-based monogenic diseases, which represent examples of different transplantation strategies, driven by the understanding of the expression of the underlying genetic defect.

Assessment of UGT polymorphisms and neonatal jaundice

Elevation of the serum bilirubin level is a common, if not universal, finding during the first week of life. This can be a transient phenomenon that resolves spontaneously or can signify a serious or even life-threatening condition. There are many causes of hyperbilirubinemia and related therapeutic and prognostic implications. The diseases in which there is a primary disorder of the metabolism of bilirubin will be reviewed regarding their clinical presentation, pathophysiology, diagnosis, and treatment. These disorders-Gilbert's syndrome and Crigler-Najjar Syndrome-both involve abnormalities in bilirubin conjugation secondary to deficiency of bilirubin uridine diphosphate glucuronosyltransferase. The purpose of this article is to review the current understanding of the genetic polymorphisms that result in these diseases and discuss recent advances in diagnosis and treatment.

Ideal Experimental Rat Models for Liver Diseases

There are many limitations for conducting liver disease research in human beings due to the high cost and potential ethical issues. For this reason, conducting a study that is difficult to perform in humans using appropriate animal models, can be beneficial in ascertaining the pathological physiology, and in developing new treatment modalities. However, it is difficult to determine the appropriate animal model which is suitable for research purposes, since every patient has different and diverse clinical symptoms, adverse reactions, and complications due to the pathological physiology. Also, it is not easy to reproduce identically various clinical situations in animal models. Recently, the Guide for the Care and Use of Laboratory Animals has tightened up the regulations, and therefore it is advisable to select the appropriate animals and decide upon the appropriate quantities through scientific and systemic considerations before conducting animal testing. Therefore, in this review article the authors examined various white rat animal testing models and determined the appropriate usable rat model, and the pros and cons of its application in liver disease research. The authors believe that this review will be beneficial in selecting proper laboratory animals for research purposes.

Paediatric liver transplantation for metabolic disorders. Part 1: Liver-based metabolic disorders without liver lesions

Liver-based metabolic disorders account for 10 to 15% of the indications for paediatric liver transplantation. In the last three decades, important progress has been made in the understanding of these diseases, and new therapies have emerged. Concomitantly, medical and surgical innovations have lead to improved results of paediatric liver transplantation, patient survival nowadays exceeding 80% 10-year after surgery with close to normal quality of life in most survivors. This review is a practical update on medical therapy, indications and results of liver transplantation, and potential future therapies, for the main liver-based metabolic disorders in which paediatric liver transplantation may be considered. Part 1 focuses on metabolic based liver disorders without liver lesions, and part 2 on metabolic liver diseases with liver lesions.

Tuberculosis in liver transplant recipients: a systematic review and meta-analysis of individual patient data

Mycobacterium tuberculosis (MTB) causes substantial morbidity and mortality in liver transplant recipients. We examined the efficacy of isoniazid latent Mycobacterium tuberculosis infection (LTBI) treatment in liver transplant recipients and reviewed systematically all cases of active MTB infection in this population. We found 7 studies that evaluated LTBI treatment and 139 cases of active MTB infection in liver transplant recipients. Isoniazid LTBI treatment was associated with reduced MTB reactivation in transplant patients with latent MTB risk factors (0.0% versus 8.2%, P = 0.02), and isoniazid-related hepatotoxicity occurred in 6% of treated patients, with no reported deaths. The prevalence of active MTB infection in transplant recipients was 1.3%. Nearly half of all recipients with active MTB infection had an identifiable pretransplant MTB risk factor. Among recipients who developed active MTB infection, extrapulmonary involvement was common (67%), including multiorgan disease (27%). The short-term mortality rate was 31%. Surviving patients were more likely to have received 3 or more drugs for MTB induction therapy (P = 0.003) and to have been diagnosed within 1 month of symptom onset (P = 0.01) and were less likely to have multiorgan disease (P = 0.01) or to have experienced episodes of acute transplant rejection (P = 0.02). Compared with the general population, liver transplant recipients have an 18-fold increase in the prevalence of active MTB infection and a 4-fold increase in the case-fatality rate. For high-risk transplant candidates, isoniazid appears safe and is probably effective at reducing MTB reactivation. All liver transplant candidates should receive a tuberculin skin test, and isoniazid LTBI treatment should be given to patients with a positive skin test result or MTB pretransplant risk factors, barring a specific contraindication. Liver Transpl 15:894-906, 2009. (c) 2009 AASLD.

Liver cell transplantation for Crigler-Najjar syndrome type I: Update and perspectives

Liver cell transplantation is an attractive technique to treat liver-based inborn errors of metabolism. The feasibility and efficacy of the procedure has been demonstrated, leading to medium term partial metabolic control of various diseases. Crigler-Najjar is the paradigm of such diseases in that the host liver is lacking one function with an otherwise normal parenchyma. The patient is at permanent risk for irreversible brain damage. The goal of liver cell transplantation is to reduce serum bilirubin levels within safe limits and to alleviate phototherapy requirements to improve quality of life. Preliminary data on Gunn rats, the rodent model of the disease, were encouraging and have led to successful clinical trials. Herein we report on two additional patients and describe the current limits of the technique in terms of durability of the response as compared to alternative therapeutic procedures. We discuss the future developments of the technique and new emerging perspectives.

Metabolic liver disease in children

The aim of this article is to provide essential information for hepatologists, who primarily care for adults, regarding liver-based inborn errors of metabolism with particular reference to those that may be treatable with liver transplantation and to provide adequate references for more in-depth study should one of these disease states be encountered.

Metabolic liver disease in children

The aim of this article is to provide essential information for hepatologists, who primarily care for adults, regarding liver-based inborn errors of metabolism with particular reference to those that may be treatable with liver transplantation and to provide adequate references for more in-depth study should one of these disease states be encountered.

Disruption of the ugt1 locus in mice resembles human Crigler-Najjar type I disease

The 9 UDP-glucuronosyltranferases (UGTs) encoded by the UGT1 locus in humans are key enzymes in the metabolism of most drugs as well as endogenous substances such as bile acids, fatty acids, steroids, hormones, neurotransmitters, and bilirubin. Severe unconjugated hyperbilirubinemia in humans that suffer from Crigler-Najjar type I disease results from lesions in the UGT1A1 gene and is often fatal. To examine the physiological importance of the Ugt1 locus in mice, this locus was rendered non-functional by interrupting exon 4 to create Ugt1(-/-) mice. Because UGT1A1 in humans is responsible for 100% of the conjugated bilirubin, it followed that newborn Ugt1(-/-) mice developed serum levels of unconjugated bilirubin that were 40-60 times higher than Ugt1(+/-) or wild-type mice. The result of extreme unconjugated bilirubin in Ugt1(-/-) mice, comparable to the induced levels noted in patients with Crigler-Najjar type 1 disease, is fatal in neonatal Ugt1(-/-) mice within 2 weeks following birth. The extreme jaundice is present as a phenotype in skin color after 8 h. Neonatal Ugt1(-/-) mice exhibit no detectable UGT1A-specific RNA, which corresponds to a complete absence of UGT1A proteins in liver microsomes. Conserved glucuronidation activity attributed to the Ugt1 locus can be defined in Ugt1(-/-) mice, because UGT2-dependent glucuronidation activity is unaffected. Remarkably, the loss of UGT1A functionality in liver results in significant alterations in cellular metabolism as investigated through changes in gene expression. Thus, the loss of UGT1A function in Ugt1(-/-) mice leads to a metabolic syndrome that can serve as a model to further investigate the toxicities associated with unconjugated bilirubin and the impact of this disease in humans.

Liver transplantation for non-hepatotoxic inborn errors of metabolism

Hepatic-based inborn errors of metabolism are targets for treatment with liver transplantation in children, in whom the metabolic defect causes irreversible damage to the liver. However, certain metabolic defects originate with enzyme deficiencies localized in the liver but then give rise to toxic intermediates that damage extrahepatic organs without any significant compromise of general liver function. Here, the rationale of using liver transplantation to replace an organ that is functioning normally except for a specific metabolic pathway raises difficult questions about indications for transplantation, timing, amount of replacement tissue needed to correct the defect, and whether heterozygote parents are suitable living donors for liver transplantation in their affected children. This review explores these questions and others, including the role of hepatocyte transplantation, in this select group of disorders. Until the promise of specific gene or enzyme replacement therapy is realized, liver and hepatocyte transplantation offers the best chance of achieving metabolic control in these challenging patients.

Liver transplantation for inborn errors of liver metabolism

Liver transplantation brings complete recovery from end-stage liver disease, and full correction of liver based inborn errors of metabolism.

Xenotransplantation of neonatal porcine liver cells

Xenotransplantation of porcine liver cell types may provide a means of overcoming the shortage of suitable donor tissues to treat hepatic diseases characterized by inherited inborn errors of metabolism or protein production. Here we report the successful isolation, culture, and xenotransplantation of liver cells harvested from 7- to 10-day-old piglets. Liver cells were isolated and cultured immediately after harvesting. Cell viability was excellent (>90%) over the duration of the in vitro studies (3 weeks) and the cultured cells continued to significantly proliferate. These cells also retained their normal secretory and metabolic capabilities as determined by continued release of albumin, factor 8, and indocyanin green (ICG) uptake. After 3 weeks in culture, porcine liver cells were loaded into immunoisolatory macro devices (Theracyte devices) and placed into the intraperitoneal cavity of immunocompetant CD1 mice. Eight weeks later, the devices were retrieved and the cells analyzed for posttransplant determinations of survival and function. Post mortem analysis confirmed that the cell-loaded devices were biocompatible, and were well-tolerated without inducing any notable inflammatory reaction in the tissues immediately surrounding the encapsulated cells. Finally, the encapsulated liver cells remained viable and functional as determined by histologic analyses and ICG uptake/release. The successful harvesting, culturing, and xenotransplantation of functional neonatal pig liver cells support the continued development of this approach for treating a range of currently undertreated or intractable hepatic diseases.

Paediatric liver transplantation--a review based on 20 years of personal experience

The natural history of most liver diseases requiring liver replacement in children is well known, and the potential of this therapy has been ascertained regarding life expectancy, which currently exceeds 90% in the long term. The timing of liver transplantation must be anticipated, to reduce the physical, psychological and mental impact of chronic liver diseases. Several studies show evidence that the best long-term results with regard to patient and graft survival are obtained with grafts procured from relatively young donors. Since the shortage of post-mortem liver donors will most likely worsen, further development of live, related-donor transplantation can be expected. The main progress to come will concern immunosuppression, taking advantage of the immunological privilege of the liver. Protocols are under development for induction of operational tolerance.

Hepatocyte transplantation in a 4-year-old girl with peroxisomal biogenesis disease: technique, safety, and metabolic follow-up

Hepatocyte transplantation is an investigational alternative to orthotopic liver transplantation to treat liver based inborn errors of metabolism. We report successful hepatocyte transplantation in a 4-year-old girl with infantile Refsum disease. Hepatocytes were isolated from the left liver segment of two male donors using a classic two-step perfusion method. Fresh cells were transplanted first and then cryopreserved cells, for a total of 2 billion cells. Total bile acids and abnormal dihydroxycoprostanoïc acid markedly decreased in the patient's serum, indicating resolution of cholestasis and re-population of liver cells. Pipecholic acid decreased by 40% and c26:c22 fatty acid ratio by 36% after 18 months. Donor chromosomes sequences were detected on biopsy posttransplant, indicating engraftment. Hepatocyte transplantation is a safe and promising technique in the treatment of rare inborn errors of metabolism. Future improvements of cell viability and prevention of apoptosis may increase engraftment and subsequent re-population.

Treatment of Crigler-Najjar type 1 disease: relevance of early liver transplantation

BACKGROUND

Crigler-Najjar syndrome type 1 (CNS1) is characterized by severe unconjugated hyperbilirubinemia from birth, caused by total failure of UDP-glucuronyltransferase activity. Only orthotopic liver transplantation (OLT) offers the prospect of cure. However, because the onset of neurologic deficits is unpredictable, timing of OLT remains difficult.

METHODS

In our transplant center, 3 patients underwent early OLT for CNS1. Two of them (7 yr, 12 yr) showed mild to moderate neurologic deficits only few weeks before OLT, another patient (4 yr) had no signs of bilirubin encephalopathy. All patients required extensive phototherapy to control bilirubin levels. Thus, OLT was performed shortly after the onset of neurologic symptoms or as a prophylactic procedure, respectively.

RESULTS

OLT was uneventful in all recipients. One of the symptomatic patients (7 yr) completely recovered from neurologic deficits at 36 months on OLT, whereas the other patient (12 yr) significantly improved symptoms at 27 months of OLT. These patients, including the 4-year-old boy, attend school at appropriate grades now.

CONCLUSIONS

Irreversible brain damage (kernicterus) may occur in the course of CNS1 disease. Because no alternative treatment options are available at this time, OLT should be performed as a preventive procedure to counteract severe CNS-related complications.

Living-related liver transplantation for Crigler-Najjar syndrome in Saudi Arabia

OBJECTIVE

To analyse the outcome of six children with Crigler-Najjar syndrome type I (CNS-I) and report the first three living-related liver transplants for this syndrome in Saudi Arabia and the Middle East.

SETTINGS

To review the medical records of six children suffering from CNS-I, three of whom underwent living-related liver transplantation (LRLT) between 22 November 1998 and January 2001.

MAIN RESULTS

Living-related liver transplantation was performed in three children with a pre-transplant unconjugated bilirubin level of 362, 381 and 502 micromol/L, respectively, despite daily phototherapy of >or= 12 h. Two of the transplanted children developed acute hepatocellular rejection, which was successfully treated with methylprednisolone pulse therapy. One tested cytomegalovirus positive (using the PP65 method), but showed no signs of clinical infection and was treated with ganciclovir. One patient had a biliary leak at the cut surface of the graft which was surgically repaired. Post-operative bilirubin levels returned to normal in all three transplanted children and no further phototherapy was required. One patient, who was not transplanted but received phototherapy, developed severe neurological damage prior to the start of our living-related liver transplant programme with a bilirubin level of 450 micromol/L, her sister is still awaiting transplantation. A 14-yr-old child with a bilirubin level of 420 micromol/L is presently undergoing phototherapy whilst awaiting orthotopic liver transplantation because of the lack of a suitable living-related donor. Six siblings of the six children in our series were reported dead by the families.

CONCLUSION

Crigler-Najjar syndrome type I is a relatively common disease in Saudi Arabia for which LRLT is a curative treatment when performed at an early age before the development of kernicterus and neurological deficiency. In countries where there is a severe shortage of cadaveric organs, as is the case in Saudi Arabia, LRLT is the optimum treatment modality for this syndrome.

Bile bilirubin pigment analysis in disorders of bilirubin metabolism in early infancy

BACKGROUND

Early and accurate diagnosis of Crigler-Najjar syndrome, which causes prolonged unconjugated hyperbilirubinaemia in infancy, is important, as orthotopic liver transplantation is the definitive treatment.

AIM

To determine whether bilirubin pigment analysis of bile in infants with prolonged unconjugated hyperbilirubinaemia provides useful diagnostic information in the first 3 months of life.

METHODS

Retrospective review of patients with prolonged unconjugated hyperbilirubinaemia referred to the liver unit, Birmingham Children's Hospital, for the diagnosis of Crigler-Najjar syndrome. Bile bilirubin pigment composition was determined by high performance liquid chromatography. Initial diagnoses were made based on the result of bile bilirubin pigment composition. Final diagnoses were made after reviewing the clinical course, response to phenobarbitone, repeat bile bilirubin pigment composition analysis, and genetic studies.

RESULTS

Between 1992 and 1999, nine infants aged less than 3 months of age with prolonged hyperbilirubinaemia underwent bile bilirubin pigment analyses. Based on these, two children were diagnosed with Crigler-Najjar syndrome (CNS) type 1, six with CNS type 2, and one with Gilbert's syndrome. Five children whose initial diagnosis was CNS type 2 had resolution of jaundice and normalisation of serum bilirubin after discontinuing phenobarbitone, and these cases were thought to be normal or to have Gilbert's syndrome. One of the initial cases of CNS type 1 responded to phenobarbitone with an 80% reduction in serum bilirubin consistent with CNS type 2. In all, the diagnoses of six cases needed to be reviewed.

CONCLUSIONS

Early bile pigment analysis, performed during the first 3 months of life, often shows high levels of unconjugated bilirubin or bilirubin monoconjugates, leading to the incorrect diagnosis of both type 1 and type 2 Crigler-Najjar syndrome.

Genetic lesions of bilirubin uridine-diphosphoglucuronate glucuronosyltransferase (UGT1A1) causing Crigler-Najjar and Gilbert syndromes: correlation of genotype to phenotype

Uridine-diphosphoglucuronate glucuronosyltransferases (UGTs) are a family of enzymes that conjugate various endogenous and exogenous compounds with glucuronic acid and facilitate their excretion in the bile. Bilirubin-UGT(1) (UGT1A1) is the only isoform that significantly contributes to the conjugation of bilirubin. Lesions in the gene encoding bilirubin-UGT(1), lead to complete or partial inactivation of the enzyme causing the rare autosomal recessively inherited conditions, Crigler-Najjar syndrome type-1 (CN-1) and type 2 (CN-2), respectively. Inactivation of the enzyme leads to accumulation of unconjugated bilirubin in the serum. Severe hyperbilirubinemia seen in CN-1 can cause bilirubin encephalopathy (kernicterus). Kernicterus can be fatal or may leave behind permanent neurological sequelae. Here, we have compiled more than 50 genetic lesions of UGT1A1 that cause CN-1 (including 9 novel mutations) or CN-2 (including 3 novel mutations) and have presented a correlation of structure to function of UGT1A1. In contrast to Crigler-Najjar syndromes, Gilbert syndrome is a common inherited condition characterized by mild hyperbilirubinemia. An insertional mutation of the TATAA element upstream to UGT1A1 results in a reduced level of expression of the gene. Homozygosity for the variant promoter is required for Gilbert syndrome, but not sufficient for manifestation of hyperbilirubinemia, which is partly dependent on the rate of bilirubin production. Several structural mutations of UGT1A1, for example, a G71R substitution, have been reported to cause mild reduction of UGT activity toward bilirubin, resulting in mild hyperbilirubinemia, consistent with Gilbert syndrome. When the normal allele of a heterozygote carrier for a Crigler-Najjar type structural mutation contains a Gilbert type promoter, intermediate levels of hyperbilirubinemia, consistent with the diagnosis of CN-2, may be observed.

Genetic lesions of bilirubin uridine-diphosphoglucuronate glucuronosyltransferase (UGT1A1) causing Crigler-Najjar and Gilbert syndromes: correlation of genotype to phenotype

Uridine-diphosphoglucuronate glucuronosyltransferases (UGTs) are a family of enzymes that conjugate various endogenous and exogenous compounds with glucuronic acid and facilitate their excretion in the bile. Bilirubin-UGT(1) (UGT1A1) is the only isoform that significantly contributes to the conjugation of bilirubin. Lesions in the gene encoding bilirubin-UGT(1), lead to complete or partial inactivation of the enzyme causing the rare autosomal recessively inherited conditions, Crigler-Najjar syndrome type-1 (CN-1) and type 2 (CN-2), respectively. Inactivation of the enzyme leads to accumulation of unconjugated bilirubin in the serum. Severe hyperbilirubinemia seen in CN-1 can cause bilirubin encephalopathy (kernicterus). Kernicterus can be fatal or may leave behind permanent neurological sequelae. Here, we have compiled more than 50 genetic lesions of UGT1A1 that cause CN-1 (including 9 novel mutations) or CN-2 (including 3 novel mutations) and have presented a correlation of structure to function of UGT1A1. In contrast to Crigler-Najjar syndromes, Gilbert syndrome is a common inherited condition characterized by mild hyperbilirubinemia. An insertional mutation of the TATAA element upstream to UGT1A1 results in a reduced level of expression of the gene. Homozygosity for the variant promoter is required for Gilbert syndrome, but not sufficient for manifestation of hyperbilirubinemia, which is partly dependent on the rate of bilirubin production. Several structural mutations of UGT1A1, for example, a G71R substitution, have been reported to cause mild reduction of UGT activity toward bilirubin, resulting in mild hyperbilirubinemia, consistent with Gilbert syndrome. When the normal allele of a heterozygote carrier for a Crigler-Najjar type structural mutation contains a Gilbert type promoter, intermediate levels of hyperbilirubinemia, consistent with the diagnosis of CN-2, may be observed.

Current status of pediatric liver transplantation

Increased survival for young liver transplant recipients has greatly improved. Increasing success has led to broader indications, thereby increasing the number of potential recipients. Pediatric liver centers are developing new strategies to cope with the ever-increasing demands for suitable size appropriate grafts. UNOS is in the process of updating guidelines to regulate the sharing of organs which become available from new surgical techniques. In the future, alternative therapies, such as artificial liver assist devices and techniques of cellular transplantation and genetic modification of hepatocytes, may decrease the number of children who die while waiting for a suitable organ or even obviate the need for the liver transplantation.

Auxiliary partial orthotopic liver transplantation for Crigler-Najjar syndrome type I

OBJECTIVE

To determine if auxiliary partial orthotopic liver transplantation (APOLT) has the long-term potential to correct the underlying abnormality in Crigler-Najjar syndrome type 1 (CNS1) without the need for total liver replacement.

BACKGROUND

Orthotopic liver transplantation has been used successfully to replace the defective enzyme in CNS1. Experimental studies have shown that only 1% to 2% of the normal hepatocyte mass is needed for bilirubin conjugation. If APOLT corrects the underlying metabolic abnormality, it has the advantage of preserving the native liver, which would serve as a "safety net" should the graft fail, and there is the potential for gene therapy in the future with possible withdrawal of immunosuppression.

METHODS

Seven APOLT procedures were performed in six recipients with CNS1. Median age at transplantation was 10.5 years. Six transplants were performed as a left auxiliary liver transplant, and one was performed as a right auxiliary liver transplant. Median serum bilirubin level at transplantation was 320 micromol/L. All patients required 12 to 16 hours of phototherapy daily before the transplant to maintain serum bilirubin levels between 250 and 350 micromol/L.

RESULTS

Median serum bilirubin level was 50 micromol/L at day 5 after the transplant and 23 micromol/L at a median follow-up of 32 months. In four children, early severe acute rejection developed, requiring conversion to tacrolimus; one underwent a second transplant for chronic rejection and graft atrophy but died from lymphoproliferative disease 6 months after the second transplant.

CONCLUSIONS

This report shows that APOLT is technically feasible and provides adequate hepatocyte mass to correct the underlying metabolic abnormality in CNS1.

Crigler-Najjar syndrome in Saudi Arabia

Crigler-Najjar (CN) syndrome is a congenital familial nonhemolytic jaundice associated with high level of unconjugated bilirubin due to deficient uridine diphosphate glucuronosyltransferase (UDPG-T) activity in the liver. The aim of this report is to emphasize the need for increased awareness of this potentially fatal condition unless diagnosed early and managed appropriately. Between 1986-1994, 12 patients (8 males and 4 females) were diagnosed at our hospital with CN syndrome. Jaundice was detected in the first few days of life in all but one, in whom detection was delayed for two weeks and resulted in kernicterus. Exchange transfusions were necessary in six cases. Consanguinity was present in 11 patients, eight of whom were the offspring of first cousins. None of the patients responded to phenobarbital therapy alone, which reflects the severity of their disease. Six patients required only phototherapy while the remaining six patients required a combination of phenobarbital and phototherapy. Percutaneous liver biopsy, performed in 10 patients, showed minimal and focal cholestasis in eight, while the remaining two had a normal histological picture. Almost complete absence of the activity of UDPGT in the liver was reported in seven cases. Kernicterus developed in five cases. It is concluded that CN syndrome remains a potentially fatal condition unless diagnosed early and managed appropriately. The recent adoption of liver segment transplantation, whether orthotopic or living-related, has saved affected patients the daily long hours of phototherapy. One of our patients successfully underwent living-related segmental liver transplantation.

Neurologic perspectives of Crigler-Najjar syndrome type I

Limited information exists on the neurologic sequelae of Crigler-Najjar syndrome type I despite this being the major morbidity of this rare autosomal recessive disorder of bilirubin conjugation that results in chronic unconjugated hyperbilirubinemia. Two patients with identical underlying genetic mutations resulting in Crigler-Najjar syndrome type I were assessed from a neurodevelopmental perspective in late childhood using age appropriate standardized measures. In addition, the English language literature of case reports and series describing the outcomes of patients with this disorder was reviewed (descriptive meta-analysis) and summarized with particular reference to neurologic symptomatology, pattern of neurologic disability, age of onset of symptoms, and therapeutic interventions. Despite radically different therapeutic interventions, our two patients did not differ in outcome measures. Review of the literature reveals distinct, often age-related, patterns of neurologic sequelae reflecting injury to basal ganglia, cerebellar, and likely hippocampal structures. Definitive prevention of the neurologic sequelae that often occur within the context of Crigler-Najjar syndrome type I requires that curative treatment (hepatic transplantation, presently, and gene therapy in the future) be applied prior to the possible onset of neurologic symptoms in adolescence.

Liver transplantation for hemochromatosis, Wilson's disease, and other metabolic disorders

Liver transplantation provides an effective means for replacing a failing liver, in addition to correcting the underlying abnormality in many metabolic disorders. Results of liver transplantation for metabolic diseases have been generally encouraging, with the exception of hereditary hemochromatosis, in which infectious and cardiac complications appear to increase post-transplant mortality. Better pretransplant diagnosis of hemochromatosis, utilizing the recently identified putative gene, may help reduce post-transplant complications. In metabolic diseases, improved understanding of the underlying genetic and molecular defects will lead to advances in medical therapy and perhaps a decreased need for liver transplantation. NTBC therapy for hereditary tyrosinemia and purified glucocerebroside therapy for Gaucher disease are two such examples. The prospects of gene therapy are being actively pursued for many metabolic diseases, such as CF, hemophilia, and familial hypercholesterolemia. Until such investigation leads directly to clinical practice, however, liver transplantation remains an effective option for therapy for a wide range of metabolic diseases.