Hereditary Unconjugated Hyperbilirubinemia Research Articles

Синдром Жильбера: термінологія, епідеміологія, генетика, патогенез (частина I)

Мета огляду — аналіз даних літератури щодо поширеності, етіології, генетики, патогенезу синдрому Жильбера. Проведений огляд наукової літератури щодо синдрому Жильбера за ключовими словами «синдром Жильбера», «гіпербілірубінемія», «уридиндифосфатглюкуронілтрансфераза» з використанням як пошукової системи PubMed. Беручи до уваги дослідження, проведені в останні 10 років, проаналізовані тези 75 статей. Більш детально вивчено результати дослідження, висвітлені у 28 статтях.

НАСЛЕДСТВЕННАЯ НЕКОНЪЮГИРОВАННАЯ ГИПЕРБИЛИРУБИНЕМИЯ (СОЧЕТАНИЕ СИНДРОМА КРИГЛЕРА-НАЙЯРА II ТИПА И СИНДРОМА ЖИЛЬБЕРА)

Background. Enzymopathic jaundices are manifested by intermittent hyperbilirubinemia, no changes in the structure of the liver, no hemolysis, Rh-conflict as well as cholestasis being noted. These jaundices include Crigler-Najjar syndrome type I, Crigler-Najjar syndrome type II and Gilbert's syndrome. They are characterized by an autosomal recessive inheritance due to the presence of mutations and polymorphisms in uridine 5'-diphosphate-glucuronosyltransferase gene (UGT1A1) leading to a decrease of the enzyme activity or to its complete loss. Objective. To demonstrate the peculiarities of diagnosis and treatment of a rare case of hereditary unconjugated hyperbilirubinemia - a combination of Crigler-Najjar syndrome type II and Gilbert's syndrome. Material and methods. Clinical observation of a patient G. aged 19, who was examined and treated at the Department of gastroenterology of a multidisciplinary hospital in Moscow in January 2021. Results. The patient G. has had icteric sclerae and skin since birth; he occasionally suffers from easy fatigability and general malaise. Physical examination revealed no changes (except for icteric discoloration). An increase in unconjugated bilirubin up to 270 μmol/L (median - 170 μmol/L) was detected. The molecular genetic study of UGT1A1 gene identified mutations in exon 4 Val378Asp (2002) and Arg108Cys as well as polymorphism 6/7TA in the promoter region, confirming the diagnosis of autosomal recessive inherited disease – a combination of Crigler Najjar syndrome type II and Gilbert's syndrome (heterozygous state), complicated by the development of hepatic encephalopathy stage 2. There was noted a significant decrease in unconjugated bilirubin up to 170.5 μmol/L, as well as improvement in general condition – reduced fatigue and weakness during the treatment with microsomal enzyme inducer (phenobarbital) and hyperammonemia corrector (ornithine aspartate). Conclusions. The use of molecular genetic analysis allows tailoring strategies for patient-specific disease diagnostics, treatment and prevention. The preservation of quality of life within satisfactory level is achieved through elimination of adverse effects provoking the development of this syndrome and through control of risk factors.

Gilbert syndrome with systemic lupus erythematosus presenting with persistent unconjugated hyperbilirubinemia: A case report.

Gilbert syndrome (GS) is a hereditary unconjugated hyperbilirubinemia that results from mutations in the bilirubin uridine diphosphate-glucuronosyltransferase (UGT1A1) gene. To the best of our knowledge, there are currently no reports that focus on patients with systemic lupus erythematosus (SLE) coexisting with GS. The present study aimed to evaluate the clinical characteristics and genotype of UGT1A1 in a Chinese patient with SLE and GS. Complete medical records and laboratory data were reviewed for a patient with SLE referred to Ruijin Hospital (Shanghai, China) for treatment between March 2016 and January 2020. Genetic analysis of the UGT1A1 gene was performed by PCR amplification and Sanger sequencing. The serum total bilirubin and unconjugated bilirubin concentrations on admission were 96.2 and 86.8 µmol/l, respectively. The homozygous mutation c.1456T>G (p.Y486D) in exon 5 was detected in this patient. The patient had a good response to phenobarbital orally at a dose of 30 mg/day and a decrease in serum bilirubin was observed. Elevated unconjugated hyperbilirubinemia in SLE needs to be differentiated from other diseases, such as GS, which can be diagnosed by UGT1A1 genetic sequencing.

Analysis of the UGT1A1 Genotype in Hyperbilirubinemia Patients: Differences in Allele Frequency and Distribution.

Objective The spectrum of UDP-glucuronyl transferase A1 (UGT1A1) variants in hereditary unconjugated hyperbilirubinemia varies markedly between different ethnic populations. This study evaluated the UGT1A1 genotypes in hyperbilirubinemia patients from southeastern China. Methods We enrolled 60 patients from southeastern China (44 men and 16 women; age range: 3–76 years) with unconjugated hyperbilirubinemia and performed genetic analysis of the UGT1A1 gene by direct sequencing. Results For patients with Gilbert syndrome, 85% (47/55) harbored pathogenic variants of UGT1A1⁎60. Both UGT1A1⁎28 and UGT1A1⁎81 were detected in the promoter region of UGT1A1. Additionally, 83% (20/24) of patients with Gilbert syndrome heterozygous for UGT1A1⁎60 had an association with heterozygous variation of UGT1A1⁎28 or UGT1A1⁎81, while 91% (21/23) of Gilbert syndrome patients homozygous for UGT1A1⁎60 had biallelic variations of UGT1A1⁎28 and UGT1A1⁎81. We detected 213 UGT1A1 allelic variants, including six novel variations, with the most frequent allele being the UGT1A1⁎60, followed by UGT1A1⁎28 and UGT1A1⁎6. All of the patients showed multiple sites of variants in UGT1A1; however, variation number was not associated with bilirubin levels (P>0.05). Conclusions The spectrum of UGT1A1 variants in southeastern Chinese patients was distinct from other ethnic populations. Our findings broaden the knowledge concerning traits associated with UGT1A1 variants and help profile genotype–phenotype correlations in hyperbilirubinemia patients.

PB2283 TREATMENT OF GILBERT SYNDROME COMPLICATED BY BLOOD DISEASES: A SERIES OF CASE REPORTS

Background:Gilbert syndrome is a mild, hereditary unconjugated hyperbilirubinemia without liver dysfunction or hemolytic anemia. It is caused by defects in the UGT1A1 gene and is one of the most prevalent congenital metabolic disorders found clinically in 3‐10% of the population.Unfortunately, some patients with blood system diseases also have Gilbert syndrome. Therefore, it is crucial to diagnose Gilbert syndrome and treat the high bilirubin levels, especially for patients who require chemotherapy or targeted drugs.Aims:To investigate the clinical characteristics and treatment of patients with Gilbert syndrome complicated by blood diseases.Methods:Peripheral blood samples were obtained from patients with Gilbert syndrome complicated by diverse blood diseases. The UGT1A1 gene was tested via sequencing before treatment; bilirubin and phenobarbitone tests were also conducted prior to treatment. Patients were then treated for their primary disease and given ursodeoxycholic acid (UDCA) either with or without phenobarbitone.Results:For patient 1(Fig. 1A), we used ursodeoxycholic acid (UDCA; 250 mg p.o. bid) to control the patient's bilirubin level while administering ATG and Cyclosporin A. After UDCA treatment was initiated, the total bilirubin and unconjugated bilirubin concentrations were approximately 43.8 μmol/l and 37.6 μmol/l, respectively. After the patient completed his ATG treatment, UDCA (250 mg p.o. qd or bid) and Cyclosporin A were used to control his bilirubin and aplastic anemia levels, respectively.For patient 2(Fig. 1B) who was confirmed to have Gilbert syndrome complicated with chronic myelogenous leukemia. Imatinib was used to control his CML, and UDCA (250 mg p.o. qd or bid) was used to control his bilirubin levels. After 1 month of treatment, he showed a hematologic response (CHR: WBC, 4.39∗109/l; PLT, 280∗109/l; basophilic granulocytes, 0.03∗109/l) without splenomegaly. After the first 3 months, he showed an optimal response according to the European Leukemia Net recommendations[5] (BCR‐ABL1/ABL1 7.23%, IS BCR/ABL1/ABL1 5.78% (ABL1 copies: 250100); Ph+ 10%). After the first 6 months, he still has an optimal response (BCR‐ABL1/ABL1 0.4%, IS BCR/ABL1/ABL1 0.32% (ABL1 copies: 237100); Ph+ 0%). At the end of 6 month treatment, the patient's total bilirubin and unconjugated bilirubin concentrations were approximately 35 μmol/l and 30 μmol/l, respectively.For the patient 3(Fig. 1C) who had high bilirubin levels complicated with chronic aplastic anemia, phenobarbitone (25 mg p.o. per day) combined with UDCA was used to control the bilirubin levels. After 1 month of treatment, his total bilirubin level decreased to 71.6 μmol/l. He was then treated with Cyclosporin A (100 mg p.o. bid) combined with phenobarbitone (12.5 mg p.o. per day) and UDCA (250 mg p.o. tid).Summary/Conclusion:These results indicate that Gilbert syndrome should be addressed when treating blood diseases. Furthermore, our results suggest that UDCA can reduce the bilirubin concentration in these patients with lower levels of bilirubin. But for patients with higher levels of bilirubin (higher than 100 μmol/l), however, UDCA is not as effective, and phenobarbitone should be added to the treatment, especially in patients requiring urgent treatment.image

Impact of higher-order heme degradation products on hepatic function and hemodynamics

Biliverdin and bilirubin were previously considered end products of heme catabolism; now, however, there is evidence for further degradation to diverse bioactive products. Z-BOX A and Z-BOX B arise upon oxidation with unknown implications for hepatocellular function and integrity. We studied the impact of Z-BOX A and B on hepatic functions and explored their alterations in health and cholestatic conditions. Functional implications and mechanisms were investigated in rats, hepatocytic HepG2 and HepaRG cells, human immortalized hepatocytes, and isolated perfused livers. Z-BOX A and B were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in acute and acute-on-chronic liver failure and hereditary unconjugated hyperbilirubinemia. Z-BOX A and B are found in similar amounts in humans and rodents under physiological conditions. Serum concentrations increased ∼20-fold during cholestatic liver failure in humans (p<0.001) and in hereditary deficiency of bilirubin glucuronidation in rats (p<0.001). Pharmacokinetic studies revealed shorter serum half-life of Z-BOX A compared to its regio-isomer Z-BOX B (p=0.035). While both compounds were taken up by hepatocytes, Z-BOX A was enriched ∼100-fold and excreted in bile. Despite their reported vasoconstrictive properties in the brain vasculature, BOXes did not affect portal hemodynamics. Both Z-BOX A and B showed dose-dependent cytotoxicity, affected the glutathione redox state, and differentially modulated activity of Rev-erbα and Rev-erbβ. Moreover, BOXes-triggered remodeling of the hepatocellular cytoskeleton. Our data provide evidence that higher-order heme degradation products, namely Z-BOX A and B, impair hepatocellular integrity and might mediate intra- and extrahepatic cytotoxic effects previously attributed to hyperbilirubinemia. Degradation of the blood pigment heme yields the bile pigment bilirubin and the oxidation products Z-BOX A and Z-BOX B. Serum concentrations of these bioactive molecules increase in jaundice and can impair liver function and integrity. Amounts of Z-BOX A and Z-BOX B that are observed during liver failure in humans have profound effects on hepatic function when added to cultured liver cells or infused into healthy rats.

The analysis of UGT1A1 gene mutations in hereditary unconjugated hyperbilirubinemia

The analysis of UGT1A1 gene mutations in hereditary unconjugated hyperbilirubinemia

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.

Compound Heterozygote of a Novel Missense Mutation (p.K402T) and a Double Missense Mutation (p.[G71R;Y486D]) in Type II Crigler‐Najjar Syndrome

362 C rigler-Najjar syndrome type II (CN-II; # Mendelian Inheritance in Man [MIM] 606785) is a moderate type of hereditary unconjugated hyperbilirubinemia caused by mutations of the bilirubin uridine diphosphate-glucuronosyltransferase gene UGT1A1 (1). Diagnosis of this syndrome is important in distinguishing it from the severe phenotype of hereditary unconjugated hyperbilirubinemia, known as Crigler-Najjar syndrome type I (CNI; MIM #218800). The serum bilirubin concentration of CN-I is more than 20 mg/dL (343mmol/L) and can reach 30 to 50 mg/dL (513–855mmol/L). Patients with CN-I are in danger of kernicterus and must receive daily phototherapy right from the neonatal period (2). They should undergo liver transplantation to avoid kernicterus. Hyperbilirubinemia in patients with CN-II is less severe than CN-I (1). The serum bilirubin concentration of CN-II is seldom harmful after the neonatal period. The serum bilirubin concentration of patients with CN-I or CN-II is often intermediate between the values specifying the 2 syndromes. Accurate diagnosis of the 2 syndromes is necessary for appropriate treatment. A phenobarbitalloading test is effective in differential diagnosis (3), but the results are not always clear, in which case genetic diagnosis is necessary. The cDNA of UGT1A1 was first cloned in 1991, and a large number of mutations have been found in patients with CN-I, CN-II, and Gilbert syndrome (GS; MIM #143500) (4,5). Mutations of UGT1A1 differ according to ethnic grouping. East Asians display many unique mutations; in particular, a major polymorphic mutation is c.211G>A: p.G71R in exon 1 of UGT1A1 (6). p.G71R reduces glucuronidation ability to less than 32% of wild type and is an important cause of Gilbert syndrome (7). One of the most important causes of CN-II in Asians is a double missense mutation, p.[G71R;Y486D] (8). This double mutation has hardly ever been detected in white and African populations.

UGT1A1(TA)n promoter polymorphism—A new case of a (TA)8 allele in Caucasians

Gilbert's syndrome is a mild hereditary unconjugated hyperbilirubinemia caused by mutations in the bilirubin UDP-glucuronosyltransferase gene (UGT1A1). The causative mutation in Caucasians is almost exclusively a TA dinucleotide insertion in the TATA box of the UGT1A1 promoter. Affected individuals are homozygous for the variant promoter and have 7 instead of 6 TA repeats. The aim of the present study was to determine the genotypes of UGT1A1(TA)n promoter polymorphism in the healthy Slovenian population and to investigate the association of genotypes with serum bilirubin levels. 236 healthy subjects were genotyped by single-strand conformation polymorphism analysis, which was validated by sequence analysis. The frequencies of genotypes were as follows: (TA)6/6 (38.1%), (TA)6/7 (47.9%), (TA)7/7 (13.6%). There was a statistically significant association of genotypes with serum bilirubin levels (p<0.001). Subjects with genotype (TA)7/7 had the highest and subjects with genotype (TA)6/6 the lowest total serum bilirubin levels. One individual in the group had the rare genotype (TA)7/8 (0.4%). Analysis of his family showed the following genotypes: (TA)6/8 in his father and sister and (TA)7/8 in his two brothers. In conclusion, the frequency of UGT1A1(TA)n promoter polymorphism genotypes was determined for the first time in the Slovenian population and is similar to frequencies observed in other Caucasian populations. The extremely rare (TA)8 allele in Caucasians was found also in Slovenians.

Two linked polymorphic mutations (A(TA)7TAA and T-3279G) of UGT1A1 as the principal cause of Gilbert syndrome.

Gilbert syndrome is a mild hereditary unconjugated hyperbilirubinemia caused by mutations in the bilirubin UDP-glucuronosyltransferase gene (UGT1A1). The mutation, A(TA)7TAA, is thought to be the sole cause of the syndrome in Caucasians, but an enhancer polymorphism (T-3279G) that lowers transcriptional activity has recently been reported. We have tested the linkage of the two mutations in 11 Caucasians and 12 Japanese patients who were homozygous for A(TA)7TAA. All 23 patients were also homozygous for T-3279G, indicating that T-3279G and A(TA)7TAA were linked. The decrease in transcription caused by both mutations together may be essential to the syndrome.

Prolonged unconjugated hyperbilirubinemia associated with breast milk and mutations of the bilirubin uridine diphosphate- glucuronosyltransferase gene.

Breast milk jaundice is a common problem in nursing infants. It has been ascribed to various breast milk substances, but the component or combination of components that is responsible remains unknown. During our study of defects of the bilirubin uridine diphosphate-glucuronosyltransferase gene (UGT1A1) in patients with hereditary unconjugated hyperbilirubinemia (Crigler-Najjar syndrome and Gilbert's syndrome) and neonatal hyperbilirubinemia, we encountered a prolonged case associated with breastfeeding; after cessation of breastfeeding, the infant's bilirubin level became normal. Genetic analysis revealed a missense mutation identical to that found in patients with Gilbert's syndrome, which usually causes jaundice after puberty. We analyzed the bilirubin UGT1A1 of infants with prolonged unconjugated hyperbilirubinemia associated with breast milk to ascertain whether genetic factors are involved. We analyzed 17 breastfed Japanese infants with apparent prolonged jaundice (total serum bilirubin concentrations above 171 micromol/L [10 mg/dL]) 3 weeks to 1 month after their birth. Except for jaundice, the infants were healthy and did not show evidence of hemolytic anemia, liver dysfunction, or hypothyroidism. After cessation of breastfeeding, the serum bilirubin concentration began to decrease in all cases. When breastfeeding was resumed, serum bilirubin concentration again became elevated in some infants, but the concentration fell to within normal by 4 months of age. We analyzed the polymerase chain reaction-amplified exon, promoter, and enhancer regions of UGT1A1 by direct sequencing. Sixteen infants had at least one mutation of the UGT1A1. Seven were homozygous for 211G-->A (G71R), which is the most common mutation detected in the East Asian population, and the mutant enzyme had one third of the normal activity. G71R is the most common missense mutation we found in our analyses in Japanese patients with Gilbert's syndrome, and it corresponds to a UGT1A1 polymorphism in the Japanese population (the allele frequency is.16). One was heterozygous for 1456T-->G (Y486D) and homozygous for 211G-->A. Six were heterozygous for 211G-->A. One was heterozygous for both 211G-->A and a TATA box mutation (A(TA)7TAA). One had a heterozygous mutation in an enhancer region (C-->A at -1353). We did not detect a homozygous A(TA)7TAA mutation, which was the most common cause of Gilbert's syndrome in European population, in this study of Japanese infants with prolonged hyperbilirubinemia triggered by breast milk. The results indicate that defects of UGT1A1 are an underlying cause of the prolonged unconjugated hyperbilirubinemia associated with breast milk. One or more components in the milk may trigger the jaundice in infants who have such mutations. The mutations we found were identical to those detected in patients with Gilbert's syndrome, a risk factor of neonatal nonphysiologic hyperbilirubinemia and a genetic factor in fasting hyperbilirubinemia.

Oral calcium phosphate: A new therapy for Crigler-Najjar disease?

BACKGROUND & AIMS: Calcium phosphate binds unconjugated bilirubin in vitro, and dietary calcium phosphate supplementation reduces the serum bilirubin level in rats with hereditary unconjugated hyperbilirubinemia (Gunn rats). The aim of this study was to evaluate the effect of oral calcium phosphate supplementation on plasma bilirubin levels in patients with Crigler-Najjar disease.METHODS: A placebo-controlled, double-blind, crossover design was used. Eleven patients, 2-42 years of age, participated. The group included 5 patients with type I disease who were all treated with phototherapy and 6 patients with type II disease who were primarily treated with phenobarbital. In addition to plasma bilirubin levels, dietary intake and urinary and fecal excretion of calcium and phosphate were evaluated.RESULTS: A modest but significant decrease in serum bilirubin was observed in patients with type I disease (18% +/- 6%, P = 0.03) but not in patients with type II disease during treatment with calcium phosphate. Urinary output of calcium and phosphate did not change during the treatment period.CONCLUSIONS: Oral calcium phosphate may be a useful adjuvant to photo- therapy in Crigler-Najjar type I disease.(Gastroenterology 1997 Feb;112(2):455-62)

Case Report of a Patient with Pseudohypoparathyroidism Associated with Slight Increase in Serum Level of Unconjugated Bilirubin

We treated a 29-year-old male patient with pseudohypoparathyroidism type I, who showed a slight increase in serum indirect bilirubin without any signs of liver dysfunction. Serum levels of total, direct and indirect bilirubins were 2.4, 0.7 and 1.7mg/dl, respectively (normal ranges: 0.2-0.8, 0-0.2 and 0.2-0.6mg/dl, respectively). The cause of the increases in serum bilirubin levels was not clear; however, hemolytic anemia, hereditary unconjugated hyperbilirubinemia or ineffective erythropoiesis were ruled out as causes for the increase, since 1) his serum level of haptoglobin was normal, 2) increase in serum level of indirect bilirubin 120 minutes after the infusion of 50mg nicotinic acid was within the normal range, and 3) severe anemia was not observed. Osmotic fragility of his circulating red blood cells was also within normal range. Three other patients with pseudohypoparathyroidism visiting our clinic also showed slightly high levels of serum indirect bilirubin, although four outpatients with idiopathic hypoparathyroidism showed no such abnormality. Abnormality in the responsiveness to parathyroid hormone and/or to that in the cyclic AMP productivity in this disease may cause the increase in the circulating unconjugated bilirubin.

Pharmacological and biological effects of tin-protoporphyrin on neonatal hyperbilirubinemic Gunn rats.

Our study was undertaken to examine the pharmacological and biological effects of tin-protoporphyrin, a competitive inhibitor of heme oxygenase, on 5- or 6-day-old homozygous (j/j) Gunn rats with hereditary unconjugated hyperbilirubinemia. When j/j neonates were injected subcutaneously with 20 mumol of tin-protoporphyrin/kg of body weight, hepatic heme oxygenase activity decreased to 30% of the initial level 2 h after administration and remained low during the next 46 h. However, the reduction of serum bilirubin was more rapid and transient, reaching the minimum value (40% of the initial level) at 1 h and increasing thereafter at a rate almost comparable to that in nontreated j/j rats. The mortality rate of j/j rats was strikingly reduced by the administration of 1 to 100 mumol of tin-protoporphyrin/kg; the most effective dose was 5 mumol/kg (8% compared with 80% in non-treated j/j rats). However, the protective effect of tin-protoporphyrin on bilirubin cerebellopathy (cerebellar hypoplasia) was less marked than expected. Possible implications of our results are discussed.