Aims. This review summarized all available evidence on the accuracy of SNP-based pathogenicity detection tools and introduced regression model based on functional scores, mutation score, and genomic variation degree. Materials and Methods. A comprehensive search was performed to find all mutations related to Crigler-Najjar syndrome. The pathogenicity prediction was done using SNP-based pathogenicity detection tools including SIFT, PHD-SNP, PolyPhen2, fathmm, Provean, and Mutpred. Overall, 59 different SNPs related to missense mutations in the UGT1A1 gene, were reviewed. Results. Comparing the diagnostic OR, our model showed high detection potential (diagnostic OR: 16.71, 95% CI: 3.38-82.69). The highest MCC and ACC belonged to our suggested model (46.8% and 73.3%), followed by SIFT (34.19% and 62.71%). The AUC analysis showed a significance overall performance of our suggested model compared to the selected SNP-based pathogenicity detection tool (P = 0.046). Conclusion. Our suggested model is comparable to the well-established SNP-based pathogenicity detection tools that can appropriately reflect the role of a disease-associated SNP in both local and global structures. Although the accuracy of our suggested model is not relatively high, the functional impact of the pathogenic mutations is highlighted at the protein level, which improves the understanding of the molecular basis of mutation pathogenesis.

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.

Successful liver transplantation in a child is often a hard-won victory, requiring all the combined expertise of a dedicated pediatric transplant team. This article outlines the considerable challenges still facing pediatric liver transplant physicians and surgeons. In looking to the future, where should priorities lie to enhance the success already achieved? First, solutions to the donor shortage must be sought aggressively by increasing the use of from split-liver transplants, judicious application of living-donor programs, and increasing the donation rate, perhaps by innovative means. The major immunologic barriers, to successful xenotransplantation make it unlikely that this option will be tenable in the near future. Second, current immunosuppression is nonspecific, toxic, and unable to be individually adjusted to the patient's immune response. The goal of achieving donor-specific tolerance will require new consideration of induction protocols. Developing a clinically applicable method to measure the recipient's immunoreactivity is of paramount importance, for future studies of new immunosuppressive strategies and to address the immediate concern of long-term over-immunosuppression. The inclusion of pediatric patients in new protocols will require the ongoing insistence of pediatric transplant investigators. Third, the current immunosuppressive drugs have a long-term morbidity and mortality of their own. These long-term effects are particularly important in children who may well have decades of exposure to these therapies. There is now some understanding of their long-term renal toxicity and the risk of malignancy. New drugs may obviate renal toxicity, whereas the risk of malignancy is inherent in any nonspecific immunosuppressive regimen. Although progress is being made in preventing and recognizing PTLD, this entity remains an important ongoing concern. The global effect of long-term immunosuppression on the child's growth, development, and intellectual potential is unknown. Of particular concern is the potential for neurotoxicity from the calcineurin inhibitors. Fourth, recurrent disease and new diseases, perhaps potentiated by immunosuppressive drugs, must be considered. Already the recurrence of autoimmune disease and cryptogenic cirrhosis have been documented in pediatric patients. Now, a new lesion, a nonspecific hepatitis, sometimes with positive autoimmune markers, that may progress to cirrhosis has been recognized. It is not known whether this entity is an unusual form of rejection, an unrecognized viral infection, or a response to immunosuppressive drugs themselves. Finally, pediatric transplant recipients, like any other children, must be protected and nourished physically and mentally if they are to fulfill their potential. After liver transplantation the child's growth, intellectual functioning, and psychologic adaptation may all require special attention from parents, teachers, and physicians alike. There is limited understanding of how the enormous physical intervention of a liver transplantation affects a child's cognitive and psychologic function as the child progresses through life. The persons caring for these children have the difficult responsibility of providing services to evaluate these essential measures of children's health over the long term and to intervene if necessary. Part of the transplant physician's our duty to protect and advocate for children is to fight for equal access to health care. In most of the developing world, economic pressures make it impossible to consider liver transplantation a health care priority. In the United States and in other countries with the medical infrastructure to support liver transplantation, however, health care professionals must strive to be sure that the policies governing candidacy for transplantation and allocation of organs are applied justly and uniformly to all children whose lives are threatened by liver disease. In the current regulatory climate that increasingly takes medical decisions out of the hands of physicians, pediatricians must be even more prepared to protect the unique and often complicated needs of children both before and after transplantation. Only in this way can the challenges of the present and the future be met.

The relative compositions of the photoisomers of bilirubin-1X alpha (4Z, 15Z-bilirubin) in serum and urine of a patient with Crigler-Najjar type I syndrome treated by phototherapy are reported. High-performance liquid chromatography analysis reveals the presence of high serum levels of the configurational bilirubin photoisomer (4Z,15E-bilirubin) before the beginning of phototherapy (between 12 and 16% of the total bilirubin). The configurational photoisomer value increases during phototherapy with blue fluorescent lamps up to a photoequilibrium of about 25%, similar to that obtained in a bilirubin solution in vitro irradiated by the same lamps. This evidence suggests an inefficient serum excretion of the 4Z,15E-bilirubin. Indeed, its average half-life in serum of the Crigler-Najjar patient is found to be about 8 h. No detectable traces of the bilirubin structural isomer, lumirubin, are found in the serum. On the other hand, lumirubin represents the dominant bilirubin isomer excreted in the urine, as both 15Z and 15E configurations. Smaller amounts of 4Z,15E-bilirubin, 4E,15Z-bilirubin and native 4Z,15Z-bilirubin are observed in urine. The presence in urine of 4Z,15Z-bilirubin is probably due to a fast reversion of the configurational photoisomers to their native form. The half-life of the configurational photoisomers in urine kept at 38 degrees C is found to be of the order of a few minutes. Our study indicates that in Crigler-Najjar type I patients, mechanisms exist to excrete all bilirubin photoisomers. The lumirubin pathway seems to contribute markedly to bilirubin excretion in the urine, as occurs in jaundiced babies under phototherapy. However, the contribution of configurational isomers cannot be neglected.

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.

Crigler-Najjar syndrome type 1 (CN type 1) is an autosomal recessive disorder characterized by nonhemolytic jaundice resulting from mutations to the gene encoding bilirubin-UDP-glucuronosyltransferase (UDPGT). The Gunn rat is an accurate animal model of this disease because the bilirubin-UDPGT gene in this strain carries a premature stop codon. The primary objective of this study was to complement this deficiency in vivo using liver-directed gene therapy. The efficiency of adenovirus type 5 (Ad5)-mediated gene transfer to the neonatal rat liver was first assessed by intravenous (i.v.) injection of an Ad5 vector carrying a nuclear-localized LacZ gene. An Ad5 vector expressing the cDNA encoding human bilirubin-UDPGT (Ad5/CMV/hUG-Br1) was then generated and injected i.v. into neonatal Gunn rats. Plasma samples were collected and bilirubin levels were determined at regular intervals. Although the mean level of bilirubin in homozygous Gunn rats 1-2 days after birth was already 14.5-fold higher than that of heterozygous siblings, treatment with Ad5/CMV/hUG-Br1 reduced plasma bilirubin to normal levels within 1 week. Plasma bilirubin in the treated homozygous rats remained normal for 4 weeks before gradually climbing to intermediate levels that were approximately half that of untreated homozygotes by 12 weeks. Administration of Ad5-mediated gene therapy to neonatal Gunn rats effectively complemented the deficiency in bilirubin-UDPGT, resulting in substantial reductions in plasma bilirubin over a 3-month period. The efficacy of Ad5-mediated gene therapy in neonates suggests that this approach might be effective against other hepatic disorders, including autosomal recessive deficiencies in lipid metabolism and vascular homeostasis.

Liver transplantation is now accepted as the standard surgical-medical treatment for end-stage liver disease, as well as replacement therapy for certain inborn errors of metabolism. While improvements in surgical methods and new immunosuppressive agents have improved survival, there remains a chronic shortage of available donor organs. This article offers guidelines for the physician, discussing indications for liver transplantation, controversial selection issues, contraindications, and finally, the future of liver transplantation.

This study represents a multicenter survey on the management of patients with Crigler-Najjar syndrome (CNS) type 1. The aim of the survey was to find guiding principles for physicians in the care of these patients. Fifty-seven patients were included. At the time of inclusion, 21 patients had received a liver transplant (37%). The average age at transplantation was 9.1 +/- 6.9 years (range, 1-23 years); the age of the patients who had not been transplanted at the time of inclusion was 6.9 +/- 6.0 years (range, 0-23 years). Brain damage had developed in 15 patients (26%). Five patients died, and 10 are alive with some degree of mental or physical handicap. In 2 patients, ages 22 and 23 years, early signs of bilirubin encephalopathy could be reversed, in 1 by prompt medical intervention followed by liver transplantation and in the other by prompt liver transplantation. Seven patients underwent transplantation with some degree of brain damage at the time of the surgery; 1 of these died after retransplantation, 2 improved neurologically, and 4 remained neurologically impaired. The age of 8 patients with and 13 without brain damage at or before transplantation was 14.3 +/- 5.9 and 5.9 +/- 5.4 years (P < .01), respectively. Therapy of CNS type 1 consists of phototherapy (12 h/d), followed by liver transplantation. Phototherapy, although initially very effective, is socially inconvenient and becomes less efficient in the older age group, thus also decreasing compliance. Currently, liver transplantation is the only effective therapy. This survey shows that, in a significant number of patients, liver transplantation is performed after some form of brain damage has already occurred. From this, one must conclude that liver transplantation should be performed at a young age, particularly in situations in which reliable administration of phototherapy cannot be guaranteed.

The Gunn rat is an excellent animal model of Crigler-Najjar syndrome, type 1. The liver and small intestine synthesize no functional bilirubin uridine diphosphoglucuronosyl transferase and, consequently, the animals cannot conjugate bilirubin. In prior studies, the authors have shown that 15- to 20-cm jejunal transplants from normal Wistar rats lowered but did not normalize serum bilirubin levels. Phenobarbital has been used to increase enzyme conjugation of bilirubin.

Phenobarbital treatment of Gunn recipients of jejunal transplants from Wistar rats normalizes serum bilirubin levels.

Forty-three Gunn recipients of jejunal transplants from Wistar rats were divided into four groups: 1) heterotopically placed grafts (Thiry-Vella loops), saline-treated, n = 14; 2) heterotopically placed grafts, phenobarbital-treated (80 mg/kg/day), n = 17; 3) orthotopically placed (in intestinal continuity) grafts, saline-treated, n = 5; and 4) orthotopically placed grafts, phenobarbital-treated, n = 7. Serum was collected before operation and weekly for 8 weeks for measurement of serum total, indirect, and direct bilirubin levels. Animals received cyclosporine, 5 micrograms/kg, daily intramuscularly.

Phenobarbital significantly augmented the bilirubin-lowering effect of heterotopic jejunal transplants (group 2). Mean total serum bilirubin fell from 9.14 +/- 0.01 to a nadir of 1.63 +/- 0.11 mg/dL at 6 weeks, after which time, levels began to rise toward baseline (as noted previously). Serum indirect bilirubin levels behaved in a similar fashion. Phenobarbital treatment "normalized" serum bilirubin levels in recipients of orthotopic Wistar jejunal grafts (group 4). Mean total serum bilirubin plummeted from 8.41 +/- 0.20 to 0.76 +/- 0.15 mg/dL at 1 week, and levels remained within the normal range for the entire 8-week study period. Identical changes were observed for serum indirect bilirubin levels.

The combination of phenobarbital treatment and orthotopic small bowel transplantation may be an appropriate therapeutic alternative to liver transplantation in the management of Crigler-Najjar syndrome, type 1.

Crigler-Najjar syndrome, type I, is a disease characterized by complete absence of hepatic bilirubin glucuronidation. The congenital indirect hyperbilirubinemia is due to an autosomal recessive deficiency of the enzyme, uridine diphosphate glucuronosyl transferase (UDPGT). The inbred homozygous Gunn rat is also deficient in UDPGT, exhibits unconjugated hyperbilirubinemia, and is an excellent animal model of the Crigler-Najjar syndrome. This study was performed to test the ability of transplanted intestine from normal Wistar rat donors to correct the deficiency in hepatic bilirubin conjugation.

In phase 1, Gunn rats underwent 40-cm heterotopic small-bowel transplants from either Wistar (experimental) or Gunn (control) rats. In phase 2, 15- to 20-cm Wistar-to-Gunn jejunal transplants were placed either heterotopically or orthotopically (in intestinal continuity). All rats were treated with cyclosporin A (CsA), 5 mg/kg per day. Serum bilirubin levels were determined spectrophotometrically at weekly intervals posttransplantation. In phase 2, UDPGT activity was quantitated at 0, 2, 4, and 8 weeks using known quantities of bilirubin as substrate.

Total bilirubin levels decreased significantly in the 40-cm heterotopic transplant recipient rats. From the initial values of 7.12 +/- 0.59 mg/dL, levels reached the nadir of 4.23 +/- 0.27 mg/dL. A parallel drop in serum levels of indirect bilirubin was noted (5.04 +/- 0.54 mg/dL to 2.74 +/- 0.23 mg/dL). After 6 weeks, bilirubin levels began to rise toward pretransplant values. In contrast, there was no significant change in bilirubin levels in the control Gunn-to-Gunn rats. Fifteen- to 20-cm heterotopic Wistar-to-Gunn transplants caused a qualitatively similar drop in total and indirect bilirubin levels. Orthotopic (in continuity) Wistar-to-Gunn transplants lowered serum bilirubin levels more rapidly, and the effect was sustained throughout the 8-week study period. By 1 week posttransplantation, total bilirubin levels dropped from 5.11 +/- 0.48 mg/dL to 2.41 +/- 0.16 mg/dL (P < 0.05); data at 8 weeks averaged 1.84 +/- 0.35 mg/dL. Respective data for indirect bilirubin levels were 4.81 +/- 0.45 mg/dL, 2.26 +/- 0.18 mg/dL, and 1.35 +/- 0.39 mg/dL. Wistar rat UDPGT activity in intestine and liver averaged 0.61 +/- 0.05 and 1.88 +/- 0.06 mg bilirubin conjugated/mg tissue per hour, respectively. Enzyme activity in the transplanted intestine persisted throughout the course of the study.

Transplants of small intestine with known UDPGT activity partially corrected the deficiency in Gunn rats and allayed the hyperbilirubinemia. Since the small intestine is known to contain small but significant amounts of a large number of predominantly hepatic enzymes, bowel transplantation may be an appropriate treatment for this and other similar genetic enzyme deficiencies.

Among the worldwide accepted indications for liver transplantation, inherited metabolic disorders play an increasing role. In some paediatric centres this indication runs second after extrahepatic biliary atresia. The aim of liver transplantation in inherited metabolic disorders is twofold: the first is to save a patient's life, the second is to accomplish phenotypic and functional cure of his disease. These aims may be achieved in disorders presenting with cirrhosis, hepatoma, life-threatening progression or failure of other organs with preserved liver function. The timing of liver transplantation has become easier with development of surgical techniques of reduced-size donor livers. These techniques enable the performance of liver transplantation with ABO blood group compatible organs of almost any size if indicated either by deterioration of liver function or impending complications such as hepatoma or life-threatening progression. In comparison with other indications such as extrahepatic biliary atresia, postnecrotic liver cirrhosis or acute liver failure, the results of transplantation in patients with inherited metabolic disorders seem to be better, reaching up to 78-95% actuarial 1-year survival rates. However, lifelong immunosuppressive therapy is necessary. This seems to be acceptable even in disorders with only partial liver function defects.

The University of Chicago program in pediatric liver transplantation continues actively to seek innovative surgical solutions to problems related to the management of children with end-stage liver disease. Among the most important problems facing these children is a shortage of donor organs, which results from three factors in addition to the actual supply of pediatric donors: the concentration of pediatric liver disease in the population younger than 2 years; the necessity for a graft that is small enough; and the epidemiology of accidents and other events that lead to organ donation. Transplantation using a liver lobe as a graft overcomes size disparity and shifts the available supply of organs from older donors to younger recipients. This work describes the technical aspects of recent innovations in the use of liver lobes in pediatric transplantation, simple reduced-size liver transplantation (RLT), split-liver transplantation (SLT), orthotopic auxiliary liver grafting (ALT), and transplantation using a living related donor (LRLT), and compares their results. Since November 1986 a total of 61 procedures have been performed in which a liver lobe was used as a graft: 26 RLT; 30 SLT, 25 in children and 5 in adults; 5 LRLT; and 1 ALT. Overall 62% of transplants performed in children have involved using a liver lobe as a graft. The rates of complications are somewhat higher than with whole-liver transplantation, but this may not be entirely the result of the complex procedures. Split liver transplantation is associated with the highest mortality and complication rates. Living related liver transplantation has been associated with complications in donors and recipients, but to date survival is 100%. Orthotopic auxiliary liver transplantation effectively corrected the metabolic defect in one patient with ornithine transcarbamylase deficiency. Overall the various modalities of using graft reduction have resulted in postoperative results similar to those achieved with full-size grafts, while pretransplantation mortality has been limited to less than 2%. Thus the use of grafts as liver lobes accomplishes the goal of reducing global mortality among children with end-stage liver disease, but at the cost of increased surgical complexity and more postoperative complications.

The University of Chicago program in pediatric liver transplantation continues actively to seek innovative surgical solutions to problems related to the management of children with end-stage liver disease. Among the most important problems facing these children is a shortage of donor organs, which results from three factors in addition to the actual supply of pediatric donors: the concentration of pediatric liver disease in the population younger than 2 years; the necessity for a graft that is small enough; and the epidemiology of accidents and other events that lead to organ donation. Transplantation using a liver lobe as a graft overcomes size disparity and shifts the available supply of organs from older donors to younger recipients. This work describes the technical aspects of recent innovations in the use of liver lobes in pediatric transplantation, simple reduced-size liver transplantation (RLT), split-liver transplantation (SLT), orthotopic auxiliary liver grafting (ALT), and transplantation using a living related donor (LRLT), and compares their results. Since November 1986 a total of 61 procedures have been performed in which a liver lobe was used as a graft: 26 RLT; 30 SLT, 25 in children and 5 in adults; 5 LRLT; and 1 ALT. Overall 62% of transplants performed in children have involved using a liver lobe as a graft. The rates of complications are somewhat higher than with whole-liver transplantation, but this may not be entirely the result of the complex procedures. Split liver transplantation is associated with the highest mortality and complication rates. Living related liver transplantation has been associated with complications in donors and recipients, but to date survival is 100%. Orthotopic auxiliary liver transplantation effectively corrected the metabolic defect in one patient with ornithine transcarbamylase deficiency. Overall the various modalities of using graft reduction have resulted in postoperative results similar to those achieved with full-size grafts, while pretransplantation mortality has been limited to less than 2%. Thus the use of grafts as liver lobes accomplishes the goal of reducing global mortality among children with end-stage liver disease, but at the cost of increased surgical complexity and more postoperative complications.

An infant became jaundiced in the neonatal period. The serum bilirubin failed to fall with phototherapy. A diagnosis of Crigler Najjar type 1 syndrome was made by exclusion and confirmed by liver biopsy. The infant has been successfully treated at home with phototherapy. Liver transplantation remains a therapeutic option.

Liver transplantation has revolutionized the field of pediatric hepatology. The present status of this therapy is reviewed in this article from a nonsurgical perspective.