Crigler-Najjar Research Articles

Repeated AAV-mediated gene transfer by serotype switching enables long-lasting therapeutic levels of hUgt1a1 enzyme in a mouse model of Crigler-Najjar Syndrome Type I.

Adeno-associated virus (AAV) -mediated gene therapy is a promising strategy to treat liver-based monogenic diseases. However, two major obstacles limit its success: first, vector dilution in actively dividing cells, such as hepatocytes in neonates/children, due to the non-integrating nature of the vector; second, development of an immune response against the transgene and/or viral vector. Crigler-Najjar Syndrome Type I is a rare monogenic disease with neonatal onset, caused by mutations in the liver-specific UGT1 gene, with toxic accumulation of unconjugated bilirubin in plasma, tissues and brain. To establish an effective and long lasting cure, we applied AAV-mediated liver gene therapy to a relevant mouse model of the disease. Repeated gene transfer to adults by AAV-serotype switching, upon neonatal administration, resulted in lifelong correction of total bilirubin (TB) levels in both genders. In contrast, vector loss over time was observed after a single neonatal administration. Adult administration resulted in lifelong TB levels correction in male, but not female Ugt1-/- mice. Our findings demonstrate that neonatal AAV-mediated gene transfer to the liver supports a second transfer of the therapeutic vector, by preventing the induction of an immune response and supporting the possibility to improve AAV-therapeutic efficacy by repeated administration.

Síndrome Lucey-Driscoll - reporte de caso

La hiperbilirrubinemia no conjugada es una condición producida por una alteración en el proceso de conjugación y excreción de la bilirr14bina. La glucoronosiltransferasa uridin difosfato es la responsable en la conjugación de la bilirrubina, es codificada por el gen de UGTlAl localizado en el brazo q del cromosoma 2 locus 37.1. La variación genética del UGTlAl puede producir diferentes fenotipos desde el más severo llamado Síndrome CriglerNajjar Tipo I y JI, pasando por el Síndrome de Gilbert; hasta una hiperbilirrubinemia transitoria neonatal o síndrome LUCEY-DRISCOLL (HBLRTFN) fenotipo OMIM 237900 con producción de kernicterus y parálisis cerebral pero con resolución espontánea, todos ellos de herencia autosómica recesiva causada por mutación homocigota o heterocigota en el gen UGTlAl. En este reporte se presenta un caso en un recién nacido que a los 7 días presenta hiperbilirrubinemia severa con kernicterus, y la prueba genética muestra mutación heterocigota del *28 del gen UGTIAl.

Clinical UGT1A1 Genetic Analysis in Pediatric Patients: Experience of a Reference Laboratory.

Neonatal hyperbilirubinemia can be severe or prolonged and warrant exploration into the underlying etiology, which may include genetic assessment of UGT1A1 for inherited disorders (i.e. Crigler-Najjar syndrome or Gilbert syndrome). In our reference laboratory, we performed UGT1A1 gene sequencing analysis on 346 pediatric patients referred for a clinical indication of hyperbilirubinemia. Males (n=241) had significantly higher mean total bilirubin concentration compared to females (n=105) (9.7 and 7.3mg/dL, respectively, p=0.042); however, no sex-based difference was observed in frequency of known or suspected reduced function UGT1A1 variants. The presence of two UGT1A1 variants (consistent with Gilbert or Crigler-Najjar syndrome) occurred less frequently in neonates (aged ≤28days) than older children (aged 1-18years) (31.3% in neonates vs. 85.1%, p<0.0001), and among neonates there was no significant difference in mean total bilirubin between those with two UGT1A1 variants and those without (p=0.47). Three novel variants, including c.337T>G (p.Y113D), c.1037C>A (p.A346E), and c.1469A>C (p.D490A) were identified. Among older children, the most common reason for referral was Gilbert syndrome (83.8%) and UGT1A1 genetic analysis confirmed a diagnosis of Gilbert syndrome in 79.0% of those children. Among neonates, a population in which hyperbilirubinemia is common and often of multifactorial etiology, UGT1A1 genetic testing served as a useful clinical tool in ruling in or ruling out inherited hyperbilirubinemia. Here we describe our experience as a reference laboratory in clinical UGT1A1 full gene sequencing. Our results highlight the challenges in predicting the contribution of genetic variation in UGT1A1 to hyperbilirubinemia based on clinical parameters alone, particularly in neonates, and the utility of UGT1A1 full gene sequencing in the evaluation of neonatal and pediatric hyperbilirubinemia.

The establishment of a high resolution melting analysis based rapid screening system for UGT1A1 gene mutation

Objective To develop a high-resolution melting (HRM) assay for rapidly screening Gilbert syndrome (GS) and Crigler-Najjar syndrome (CNS) associated with UGT1A1 defects. Method Methodology was developed. Then, we applied the established method to analyze 61 clinical samples from neonatal patients with severe unexplained unconjugated hyperbilirubinemia. Neonates with known risk factors for developing hyperbilirubinemia, such as ABO hemolysis, G6PD deficiency, sepsis, hypoxic ischemic encephalopathy were excluded. Five pairs of PCR primers were designed to detect the five common mutations (G211A, C686A, C1091T, C1352T and T1456G) in Asia population. PCR and HRM Assay conditions were optimized. UGT1A1 genotyping in clinical samples was performed by using the established HRM analysis, and all results were subsequently confirmed by direct DNA sequencing. Results The mutants were readily differentiated by using HRM analysis. In this study, 42 neonates were identified with UGT1A1 mutation, and 4 different known variants were detected. Conclusion HRM analysis in this study was economical, convenient, rapid, effective for screening UGT1A1 gene mutations, which can serve as an reliable method for the clinical diagnosis of GS and CNS and the large-scale molecular epidemiological research of UGT1A1 gene-related diseases.(Chin J Lab Med, 2017, 40: 101-104) Key words: Gilbert disease; Crigler-Najjar syndrome; Hyperbilirubinemia, neonatal; Glucuronosyltransferase; Mutation; Polymerase chain reaction; High resolution melting

Unusual Indications for a Liver Transplant: A Single-Center Experience.

This study sought to evaluate the efficacy of liver transplant for unusual liver diseases. The results of 476 patients who underwent liver transplant from 1988 to January 2015 were retrospectively analyzed. Two hundred forty-five of them were adult patients and 231 of them were pediatric. Thirty-one patients had unusual liver disease. Of the 31 patients with unusual liver disease, 9 (29%) were adult and 22 (71%) were pediatric patients. In the pediatric group, indications for liver transplant were Alagille syndrome (n = 5), Crigler-Najjar syndrome type 1 (n = 5), glycogen storage disease (n = 3), oxalosis (n = 3), familial hypercholesterolemia (n = 2), alpha-1-antitrypsin deficiency (n = 2), Caroli disease (n = 1), and cystic neuroblastoma metastasis (n = 1). Six patients (27.2%) had acute rejection episodes and were successfully treated with pulse steroids. In 2 patients, retransplant was performed for chronic rejection. Three patients died during follow-up (13.6%): 2 because of sepsis and 1 because of cranial hemorrhage. In the adult group, indications for liver transplant were neuroendocrine tumor metastasis (n = 1), liver angiosarcoma (n = 1), familial hypercholesterolemia (n = 2), alveolar hydatid disease (n = 2), cystic fibrosis (n = 1), congenital hepatic fibrosis (n = 1), and oxalosis (n = 1). Four patients (44.4%) had acute rejection episodes and were successfully treated with pulse steroid therapy. One patient died due to the recurrence of primary disease (liver angiosarcoma) during follow-up (11.1%). Advances in liver transplant and our understanding about unusual liver disease have led to significant improvements in managing these diseases. Liver transplant effectively treats the underlying defect and the complications of portal hypertension, or risk of malignancy for those disorders, in which the liver is affected.

UGT1A1 polymorphisms in cancer: impact on irinotecan treatment.

Mutations in the UGT1A1 gene have been implicated in Gilbert syndrome, which shows mild hyperbilirubinemia, and a more aggressive childhood subtype, Crigler–Najjar syndrome. To date, more than 100 variants have been found in the UGT1A1 gene. Among them, UGT1A1*28 and UGT1A1*6 have been reported to be associated with severe toxicities in patients treated with irinotecan-based chemotherapy by increasing the dose of SN-38 (7-ethyl-10-hydroxycamptothecin), an active form of irinotecan. Many association studies and meta-analyses have demonstrated the contribution of UGT1A1*28 and UGT1A1*6 polymorphisms to the toxicities caused by irinotecan-based therapy. The aim of this review was to evaluate the impact of these variants upon the toxicities and the efficacy of irinotecan-based chemotherapy.

Death from pulmonary embolism of cyanoacrylate glue following gastric varix endoscopic injection

We present the case of a 25year old woman with a complex past medical history including Crigler-Najjar syndrome (Type 1) with a liver transplant in 1993 and subsequent development of cirrhosis with portal hypertension in the transplanted liver. The deceased presented to hospital with hematemesis and investigations showed a large gastric varix. The varix was injected with cyanoacrylate glue. Within 30min of injection the patient became acutely hypoxic. Urgent chest X-ray demonstrated radio opaque glue within the pulmonary arteries. It was evident that future treatment was futile and supportive treatment was withdrawn. The deceased was referred for medico legal post mortem examination. The post mortem CT scan performed prior to autopsy showed widespread radio-opaque material within the pulmonary arteries. At autopsy, rubbery grey/tan "clot" occluded the major proximal and segmental pulmonary arteries. Microscopic examination of the "clot" showed clumps of erythrocytes surrounded by foreign material. We discuss this relatively uncommon but well recognized complication of variceal injection with cyanoacrylate glue.

Intense blue light therapy during the night-time does not suppress the rhythmic melatonin biosynthesis in a young boy.

Melatonin is a hormone predominantly synthesized and secreted during the night by the pineal gland. Artificial light at night, especially its blue part, acutely suppresses the melatonin production. Th e aim of the present study was to find out, whether an intense blue light phototherapy of severe hyperbilirubinemia, may suppress the melatonin production during the night when the eyes will be properly protected by a sleep mask. The main melatonin metabolite, 6-sulphatoxymelatonin was measured in urine in a nine-year old boy suffering from the Crigler-Najjar syndrome type I. The boy was treated during the sleep period with an intense blue light (to 1800 lx) 10 h/day, since his birth. During the phototherapy, his eyes were protected with a sleep mask. The concentration of 6-sulphatoxymelatonin was determined in the first morning urine and urine collected afternoon during the six days. The patient was exposed to phototherapy for three nights, two nights without and the last one with the treatment. The control urine samples were obtained from 8 healthy nine-year old boys. The level of 6-sulphatoxymelatonin was measured by radioimmunoassay and the data were normalized to urinary creatinine. A distinct melatonin production rhythm was found and 6-sulphatoxymelatonin concentration in urine of the patient was comparable with the values obtained by the control group. No differences in 6-sulphatoxymelatonin levels were found between the nights with and without the phototherapy applied. We conclude that the whole night treatment of hyperbilirubinemia with intense blue light has negligible side effect on the rhythmic melatonin production, when the eyes are sufficiently protected by the sleep mask.

Crigler-Najjar Syndrome: A Rare Fatality

This paper reviews Crigler-Najjar Syndrome as a rare fatality affecting individuals in the early years of life. It’s rare incidence, mis-diagnosis and severe complications resulting in death at the early age has cause difficulty in determining its exact frequency in general population. This syndrome, is described by the accumulation of un-conjugated bilirubin in the body due to the inheritance of defects UGT1A1 genes. This anomaly disrupts the bilirubin mechanism at a greater extent. The high level of bilirubin in the body manifests itself in terms of specific signs and symptoms among which jaundice is most common and well-known. Therefore, treatment is primarily directed towards decreasing accumulation of un-conjugated bilirubin in the body. Aspects of liver transplant can be seen as permanent treatment plan at risk to benefit ratio.

The treatment of crigler-najjar syndrome by blue light as explained by resonant recognition model

The Crigler-Najjar syndrome is extremely rare genetic disease, that is manifested by severe jaundicedue to lack of UDP glucuronosyltransferase 1-A1 (UDP) activity. The main treatment is to use the blue lightphototherapy, during the prolong time, during the day every day. Here, we analyzed human UDP’s correlation with the blue light phototherapy using the nonlinear physico-mathematical model: Resonant Recognition Model (RRM), which proposes that protein activation is electromagnetic in nature within the frequency range of infrared and visible light. We found that human UDP’s are characterized by specific RRM frequency that is related to the blue light radiation. This could be the explicit explanation, why phototherapy with the blue light could replace lack of UDP activity. However, the blue light treatment is less effective with ageing, due to decrease of the blue lightpenetration through skin. Thus, there is a need for alternative treatments. Here, we propose to design de-novopeptide, using this specific RRM frequency. Such peptide, according to RRM, is proposed to have the samebiological function as UDP glucuronosyltransferase 1-A1 and thus can be used for alternative treatment of Crigler-Najjar syndrome.

Gunn Rats as a Surrogate Model for Evaluation of Hepatocyte Transplantation-Based Therapies of Crigler-Najjar Syndrome Type 1.

Liver transplantation has been established as a curative therapy for acute and chronic liver failure, as well as liver-based inherited metabolic diseases. Because of the complexity of organ transplantation and the worldwide shortage of donor organs, hepatocyte transplantation is being developed as a bridging therapy until donor organs become available, or for amelioration of inherited liver-based diseases. The Gunn rat is a molecular and metabolic model of Crigler-Najjar syndrome type 1, which is characterized by lifelong unconjugated hyperbilirubinemia due to the lack of uridinediphosphoglucuronate glucuronosyltransferase-1 (UGT1A1)-mediated bilirubin glucuronidation. Gunn rats are convenient for evaluating the effect of hepatocyte transplantation or gene therapy, because the extent of UGT1A1 replacement can be assessed by serial determination of serum bilirubin levels, and excretion of bilirubin glucuronides in bile provide definitive evidence of the function of the transplanted hepatocytes or the effect of gene therapy. The core techniques involved in hepatocyte transplantation in Gunn rats are discussed in this chapter.

158. Cryptic ATG Removal from Synthetic Introns Increase the Therapeutic Efficacy of AAV Vector Mediated Gene Transfer

Inclusion of synthetic introns in adeno-associated virus (AAV) vector expression cassettes is a commonly used maneuver to drive increased transgene expression, possibly via an increased stability and/or increased nuclear translocation of mRNA. Although the positive effect of intronic sequences on transgene expression has been demonstrated in several models, less clear is whether splicing in these synthetic expression cassettes occurs with 100% efficiency and if the presence of the unspliced intron can influence the efficiency of translation of the transgene. In an effort to optimize a liver gene transfer approach to treat Crigler-Najjar (CN) syndrome, an autosomal recessive disorder caused by mutations in the UDP-glucuronosyltransferase 1 isotype A1 (UGT1A1) gene, we analyzed the sequence of a synthetic intron derived from human beta-globin intron 2 (hBB2) for motifs that may affect the transgene expression levels. This analysis revealed the presence of out of frame and in frame ATG codons before the start site of the UGT1A1 transgene. Unexpectedly, the removal of these cryptic ATGs from the intronic sequence enhanced transgene expression, which resulted in stable, long-term correction of serum bilirubin levels in animal models of CN syndrome. These results demonstrate that intron optimization increases mRNA and protein levels in vitro and enhance the efficacy of the vector in vivo. Next, we conducted a similar analysis on other intronic sequences commonly used in AAV-mediated gene transfer, showing that the removal of cryptic ATGs in the intron at the 5’ of a transgene generally increases its expression. The scanning ribosome model may provide a solid explanation for our findings given that the intronic sequence is not completely removed by splicing. We thus analyzed the structure of the region at the 5’ of the transgene by RT-PCR and primer elongation assay and we observed the accumulation of unspliced forms of the mRNA. We also confirmed that the presence of cryptic ATGs has a critical impact on the translation efficiency of the transgene. In conclusion, our results confirm the positive effect of an intron fused to the 5’ of a transgene on its expression levels. On the other hand, our results provide evidence that the synthetic introns used in gene therapy are not spliced with 100% efficiency, thus the optimization of the sequence of the intron by removal of cryptic ATGs is important to increase the transgene expression in AAV vector-mediated gene transfer.

Genotype of UGT1A1 and phenotype correlation between Crigler-Najjar syndrome type II and Gilbert syndrome.

Hereditary unconjugated hyperbilirubinemias, Crigler-Najjar syndrome type I, Crigler-Najjar syndrome type II (CN-2), and Gilbert syndrome (GS) all result from mutations of the bilirubin uridine 5'-diphosphate (UDP)-glucuronosyltransferase gene (UGT1A1). Often, to distinguish between CN-2 and GS is difficult because the borderline of the two syndromes is unclear. We analyzed the genotypes and phenotypes of 163 Japanese patients with CN-2 or GS. Japanese patients (99 males and 64 females) with unconjugated hyperbilirubinemia were analyzed. Their serum bilirubin concentrations varied from 1.2 to 22.2 mg/dL (20 to 379 μM). Genetic analysis of UGT1A1 was performed by PCR-amplified direct sequencing. Association between serum bilirubin concentrations and genotypes group (typical CN-2, intermediate group, and typical GS) was studied. Most patients had biallelic mutations of UGT1A1. Moreover, many of them (78.5%) had multiple mutations. The mutation in typical CN-2 was a homozygous double missense mutation of p.[G71R:Y486D]. In typical GS group, four prevalent genotypes were detected: homozygous UGT1A1*28, UGT1A1*6/UGT1A1*28, and homozygous UGT1A1*6, and UGT1A1*27/UGT1A1*28. In the intermediate group, three genotypes, p.[G71R:Y486D]/UGT1A1*7, p.[G71R:Y486D]/UGT1A1*6, and homozygous UGT1A1*7, were detected. Serum bilirubin concentrations of typical CN-2, intermediate group, and typical GS are respectively 12.9 ± 5.1, 5.2 ± 2.2, and 2.8 ± 1.1 mg/dL. Serum bilirubin concentration among the three groups is statistically different (P < 0.0001). The serum bilirubin concentration varied continuously from GS to CN-2 depending on genotypes. Because of the combination of the mutations and polymorphisms, many patients showed intermediate serum bilirubin concentration between two syndromes. Clinically, it is difficult to distinguish clearly between the two syndromes.

A translationally optimized AAV-UGT1A1 vector drives safe and long-lasting correction of Crigler-Najjar syndrome

Crigler-Najjar syndrome is a severe metabolic disease of the liver due to a reduced activity of the UDP Glucuronosyltransferase 1A1 (UGT1A1) enzyme. In an effort to translate to the clinic an adeno-associated virus vector mediated liver gene transfer approach to treat Crigler-Najjar syndrome, we developed and optimized a vector expressing the UGT1A1 transgene. For this purpose, we designed and tested in vitro and in vivo multiple codon-optimized UGT1A1 transgene cDNAs. We also optimized noncoding sequences in the transgene expression cassette. Our results indicate that transgene codon-optimization is a strategy that can improve efficacy of gene transfer but needs to be carefully tested in vitro and in vivo. Additionally, while inclusion of introns can enhance gene expression, optimization of these introns, and in particular removal of cryptic ATGs and splice sites, is an important maneuver to enhance safety and efficacy of gene transfer. Finally, using a translationally optimized adeno-associated virus vector expressing the UGT1A1 transgene, we demonstrated rescue of the phenotype of Crigler-Najjar syndrome in two animal models of the disease, Gunn rats and Ugt1a1-/- mice. We also showed long-term (>1 year) correction of the disease in Gunn rats. These results support further translation of the approach to humans.

Inherited disorders of bilirubin clearance

Inherited disorders of hyperbilirubinemia may be caused by increased bilirubin production or decreased bilirubin clearance. Reduced hepatic bilirubin clearance can be due to defective (i) unconjugated bilirubin uptake and intrahepatic storage, (ii) conjugation of glucuronic acid to bilirubin (e.g., Gilbert syndrome, Crigler-Najjar syndrome, Lucey-Driscoll syndrome, breast milk jaundice), (iii) bilirubin excretion into bile (Dubin-Johnson syndrome), or (iv) conjugated bilirubin re-uptake (Rotor syndrome). In this review, the molecular mechanisms and clinical manifestations of these conditions are described, as well as current approaches to diagnosis and therapy.

Differentiating Gilbert Syndrome from Crigler Najjar Syndrome Type 2 by Phenobarbitone Test

Gilbert syndrome characterized by jaundice with intermittent elevations of indirect bilirubin, in the absence of haemolysis or underlying liver disease, has both autosomal dominant and recessive inheritance. Crigler-Najjar syndrome type II (CNS2) is a hereditary disorder of bilirubin metabolism characterized by unconjugated hyperbilirubinemia due to reduced and inducible activity of hepatic bilirubin glucuronosyltransferase (GT). We report 20 children between age 5 to 15 years with unconjugated hyperbilirubenemia who were given seven days of oral phenobarbitone (5mg/kg/day) and decrease in level of bilirubin was noted. There was only 30-40% reduction of bilirubin in Crigler Najjar Syndrome Type 2 compared to Gilberts Syndrome in which bilirubin level normalised. This case series highlights the importance of simple test to differentiate these two conditions. This test is also very helpful in a place where enzyme level and mutational study cannot be done.J Nepal Paediatr Soc 2015;35(1):82-84

Performance of In Silico Tools for the Evaluation of UGT1A1 Missense Variants.

Variations in the gene encoding uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) are particularly important because they have been associated with hyperbilirubinemia in Gilbert's and Crigler-Najjar syndromes as well as with changes in drug metabolism. Several variants associated with these phenotypes are nonsynonymous single-nucleotide polymorphisms (nsSNPs). Bioinformatics approaches have gained increasing importance in predicting the functional significance of these variants. This study was focused on the predictive ability of bioinformatics approaches to determine the pathogenicity of human UGT1A1 nsSNPs, which were previously characterized at the protein level by in vivo and in vitro studies. Using 16 Web algorithms, we evaluated 48 nsSNPs described in the literature and databases. Eight of these algorithms reached or exceeded 90% sensitivity and six presented a Matthews correlation coefficient above 0.46. The best-performing method was MutPred, followed by Sorting Intolerant from Tolerant (SIFT). The prediction measures varied significantly when predictors such us SIFT, polyphen-2, and Prediction of Pathological Mutations on Proteins were run with their native alignment generated by the tool, or with an input alignment that was strictly built with UGT1A1 orthologs and manually curated. Our results showed that the prediction performance of some methods based on sequence conservation analysis can be negatively affected when nsSNPs are positioned at the hypervariable or constant regions of UGT1A1 ortholog sequences.

Amelioration of Hyperbilirubinemia in Gunn Rats after Transplantation of Human Induced Pluripotent Stem Cell-Derived Hepatocytes

SummaryHepatocyte transplantation has the potential to cure inherited liver diseases, but its application is impeded by a scarcity of donor livers. Therefore, we explored whether transplantation of hepatocyte-like cells (iHeps) differentiated from human induced pluripotent stem cells (iPSCs) could ameliorate inherited liver diseases. iPSCs reprogrammed from human skin fibroblasts were differentiated to iHeps, which were transplanted into livers of uridinediphosphoglucuronate glucuronosyltransferase-1 (UGT1A1)-deficient Gunn rats, a model of Crigler-Najjar syndrome 1 (CN1), where elevated unconjugated bilirubin causes brain injury and death. To promote iHep proliferation, 30% of the recipient liver was X-irradiated before transplantation, and hepatocyte growth factor was expressed. After transplantation, UGT1A1+ iHep clusters constituted 2.5%–7.5% of the preconditioned liver lobe. A decline of serum bilirubin by 30%–60% and biliary excretion of bilirubin glucuronides indicated that transplanted iHeps expressed UGT1A1 activity, a postnatal function of hepatocytes. Therefore, iHeps warrant further exploration as a renewable source of hepatocytes for treating inherited liver diseases.

Human neonatal hepatocyte transplantation induces long-term rescue of unconjugated hyperbilirubinemia in the Gunn rat.

Crigler-Najjar type 1 disease is a rare inherited metabolic disease characterized by high levels of unconjugated bilirubin due to the complete absence of hepatic uridine diphosphoglucuronate-glucuronosyltransferase activity. Hepatocyte transplantation (HT) has been proposed as an alternative treatment for Crigler-Najjar syndrome, but it is still limited by the quality and the low engraftment and repopulation ability of the cells used. Because of their attachment capability and expression of adhesion molecules as well as the higher proportion of hepatic progenitor cells, neonatal hepatocytes may have an advantage over adult cells. Adult or neonatal hepatocytes were transplanted into Gunn rats, a model for Crigler-Najjar disease. Engraftment and repopulation were studied and compared by immunofluorescence (IF). Additionally, the serum bilirubin levels, the presence of bilirubin conjugates in rat serum, and the expression of uridine diphosphate glucuronosyltransferase 1 family polypeptide A1 (UGT1A1) in rat liver samples were also analyzed. Here we show that neonatal HT results in long-term correction in Gunn rats. In comparison with adult cells, neonatal cells showed better engraftment and repopulation capability 3 days and 6 months after transplantation, respectively. Bilirubinemia decreased in the transplanted animals during the whole experimental follow-up (6 months). Bilirubin conjugates were also present in the serum of the transplanted animals. Western blots and IF confirmed the presence and expression of UGT1A1 in the liver. This work is the first to demonstrate the advantage of using neonatal hepatocytes for the treatment of Crigler-Najjar in vivo.

Spectrum of UGT1A1 Variations in Chinese Patients with Crigler-Najjar Syndrome Type II.

Crigler–Najjar Syndrome type II (CNS-II) is an autosomal recessive hereditary condition of unconjugated hyperbilirubinemia without hemolysis, with bilirubin levels ranging from 102.6 μmol/L to 342 μmol/L. CNS-II is caused by a deficiency of UDP-glucuronyl transferase (UGT), which is encoded by the UDP-glucuronyl transferase 1A1 gene (UGT1A1). In East Asian populations, the compound homozygous UGT1A1 G71R and Y486D variants are frequently observed in cases with bilirubin levels exceeding 200 μmol/L. In this study, we investigated the spectrum of UGT1A1 variations in Chinese CNS-II patients. We sequenced the enhancer, promoter, and coding regions of UGT1A1 in 11 unrelated Chinese CNS-II patients and 80 healthy controls. Nine of these patients carried variations that are here reported for the first time in CNS-II patients, although they have been previously reported for other types of hereditary unconjugated hyperbilirubinemia. These individual variations have less influence on UGT activity than do the compound homozygous variation (combination of homozygous G71R variant and Y486D variant). Therefore, we propose that the spectrum of UGT1A1 variations in CNS-II differs according to the bilirubin levels.