Gilbert's syndrome

The molecular basis of jaundice: An old symptom revisited

Increased serum bilirubin level is a widely used diagnostic marker for hepatic illnesses. Nevertheless, mild elevation of unconjugated serum bilirubin (such as in Gilbert syndrome) has been recently demonstrated to correlate with low risk of chronic inflammatory and/or oxidative stress-mediated diseases. In accord, a low serum bilirubin level has emerged as an important predisposing factor or a biomarker of these pathologic conditions including cardiovascular, tumour, and possibly neurodegenerative diseases. Bilirubin possesses multiple biological actions with interaction in a complex network of enzymatic and signalling pathways. The fact that the liver is the main organ controlling the bioavailability of bilirubin emphasizes the central role of this organ in human health.

ACG Clinical Guideline: Evaluation of Abnormal Liver Chemistries

Clinicians are required to assess abnormal liver chemistries on a daily basis. The most common liver chemistries ordered are serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and bilirubin. These tests should be termed liver chemistries or liver tests. Hepatocellular injury is defined as disproportionate elevation of AST and ALT levels compared with alkaline phosphatase levels. Cholestatic injury is defined as disproportionate elevation of alkaline phosphatase level as compared with AST and ALT levels. The majority of bilirubin circulates as unconjugated bilirubin and an elevated conjugated bilirubin implies hepatocellular disease or cholestasis. Multiple studies have demonstrated that the presence of an elevated ALT has been associated with increased liver-related mortality. A true healthy normal ALT level ranges from 29 to 33 IU/l for males, 19 to 25 IU/l for females and levels above this should be assessed. The degree of elevation of ALT and or AST in the clinical setting helps guide the evaluation. The evaluation of hepatocellular injury includes testing for viral hepatitis A, B, and C, assessment for nonalcoholic fatty liver disease and alcoholic liver disease, screening for hereditary hemochromatosis, autoimmune hepatitis, Wilson's disease, and alpha-1 antitrypsin deficiency. In addition, a history of prescribed and over-the-counter medicines should be sought. For the evaluation of an alkaline phosphatase elevation determined to be of hepatic origin, testing for primary biliary cholangitis and primary sclerosing cholangitis should be undertaken. Total bilirubin elevation can occur in either cholestatic or hepatocellular diseases. Elevated total serum bilirubin levels should be fractionated to direct and indirect bilirubin fractions and an elevated serum conjugated bilirubin implies hepatocellular disease or biliary obstruction in most settings. A liver biopsy may be considered when serologic testing and imaging fails to elucidate a diagnosis, to stage a condition, or when multiple diagnoses are possible.

Liver transplantation from living donors with Gilbert's syndrome is a safe procedure for both donors and recipients

Liver transplantation (LT) has become a favorable therapeutic option for patients with end-stage liver diseases. Gilbert's syndrome (GS) is a benign condition characterized by intermittent mild jaundice due to unconjugated hyperbilirubinemia. It is not obvious whether living-donor liver transplantation (LDLT) from a donor with GS could result in a normal outcome for both the recipient and the donor. We aimed to determine whether right lobe hepatectomy is a safe procedure for living donors with GS and LT recipients. Between September 2011 and March 2015, 305 LDLT procedures using right lobe grafts were performed at Atasehir Memorial Hospital, Istanbul, Turkey. Nineteen of 305 LT candidates who had been diagnosed with GS were included in the current study. After a 12-h overnight fast, total and indirect bilirubin levels of donors and recipients were measured. The median follow-up after transplant was 16 months (range 3-36 months). The median age of donors was 25 (range 20-55 yr). Four donors (21%) were female, and 15 donors (89%) were male. The median age of donors was 51 (range 23-68 yr). Eleven recipients (57%) were female, and 8 (43%) were male. The median preoperative total bilirubin level of donors was 1.69 mg/dL (range 1.26-2.43 mg/dL) (normal range <1.2 mg/dL). The median total bilirubin level of donors on postoperative day 7 was 1.04 mg/dL (range 0.71-3.23 mg/dL). As our study has included a large number of donors with GS, it produced reliable evidence that right lobe hepatectomy is a safe procedure for living donors with GS and LT recipients.

Colorful DNA polymorphisms in humans

In this review article we summarize current knowledge on how variation on the DNA level influences human pigmentation including color variation of iris, hair, and skin. We review recent progress in the field of human pigmentation genetics by focusing on the genes and DNA polymorphisms discovered to be involved in determining human pigmentation traits, their association with diseases particularly skin cancers, and their power to predict human eye, hair, and skin colors with potential utilization in forensic investigations.

Can an extended right lobe be harvested from a donor with Gilbert's syndrome for living-donor liver transplantation? Case report

Gilbert's syndrome (GS) is a common cause of inherited benign unconjugated hyperbilirubinemia that occurs in the absence of overt hemolysis, other liver function test abnormalities, and structural liver disease. GS may not affect a patient's selection for living-donor liver transplantation (LDLT). Between February 2005 and April 2011, 446 LDLT procedures were performed at our institution. Two of the 446 living liver donors were diagnosed with GS. Both donors underwent extended right hepatectomies, and donors and recipients experienced no problem in the postoperative period. Their serum bilirubin levels returned to the normal range within 1-2 weeks postoperatively. In our opinion, extended right hepatectomy can be performed safely in living liver donors with GS if appropriate conditions are met and remnant volume is >30%. Livers with GS can be used successfully as grafts in LDLT recipients.

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.

The inverse starving test is not a suitable provocation test for Gilbert's syndrome

Background

Introduction

The aim of this study was to evaluate a simple diagnostic test for Gilbert's syndrome (GS), which avoids hospitalization and exposure to toxic test substrates. GS is the most frequent cause of isolated unconjugated hyperbilirubinemia. The nicotinic acid test and the starving test are established approaches to diagnose GS. However, these tests cause considerable side effects or require hospital admission. In single GS patients, we observed rapid serum bilirubin normalization after a standard European lunch (the "inverse starving test").

Findings

At two consecutive days, 18 profoundly characterized GS patients (7 females, 11 males, median age 34.5 years, range 21–58 years) were investigated with the nicotinic acid test and the inverse starving test. Unconjugated serum bilirubin (UCB) levels were measured before and hourly up to four hours after lunch (median 645 kcal), and after the ingestion of 170 milligrams nicotinic acid, respectively. Patients who consulted their physicians with jaundice were significantly more likely to undergo invasive diagnostic procedures than patients with an incidental finding of elevated UCB, despite UCB levels were indifferent in both groups. Two hours after nicotinic acid ingestion, relative UCB exceeded 1.7 fold the fasting levels (median, range 0.9–2.4 fold, sensitivity 83%). In the inverse starving test, UCB remained almost unchanged three hours after lunch (median 1.0; range: 0.8–1.2 fold). Molecular analysis established the genotype of the TATAA box of the UGT1A1 gene; all patients carried an UGT1A1 promotor polymorphism.

Conclusion

The inverse starving test is not an appropriate provocation test for patients with suspected GS. The 100% prevalence of the UGT1A1 polymorphism in our cohort underlines that the diagnosis of GS may be substantiated with this simple molecular test in patients with an uncertain diagnosis of GS.

A shortened, 2-hour rifampin test: a useful tool in Gilbert's syndrome

INTRODUCTION

Diagnosis of Gilbert's disease often involves unnecessary testing and patient anxiety. Rifampin test can support the diagnosis; it has been described in short series and lacks standardization in dose, collection times, result presentation and interpretation. Our objective was to compare the response to oral rifampin in a series of patients with Gilbert's disease, 2 and 4 h after drug administration.

PATIENTS AND METHODS

Eighty-nine patients with Gilbert's disease (elevated total bilirubin with no hepatopathy or hemolysis) were recruited. After a basal blood collection, 900 mg rifampin were administered per os and new samples were drawn 2 and 4 h later. Total and esterified bilirubin were measured in every sample. Haptoglobin concentration was also analyzed.

RESULTS

When expressed as relative increase with respect to basal values, variations observed 2 h after rifampin intake were all above 15%. A significant correlation (r = 0.902; p = 0.000) was found between relative increases 2 and 4 h after drug administration. No significant variations were found in haptoglobin concentrations.

CONCLUSION

Rifampin test is useful in diagnosing Gilbert's disease, but variations in total bilirubin concentrations (basal and post-rifampin) make that no absolute cut-off value can be used. Correlation between 2- and 4-h relative increases suggests that a shortened version could simplify the test.

Unconjugated bilirubin induces apoptosis in colon cancer cells by triggering mitochondrial depolarization

Bilirubin is the principal end product of heme degradation. Prompted by epidemiologic analyses demonstrating an inverse correlation between serum bilirubin levels and cancer mortality, we examined the effect(s) of bilirubin on the growth and survival of colon adenocarcinoma cells. Adenocarcinoma cell monolayers were treated with bilirubin over a range of bilirubin:BSA molar ratios (0-0.6), and viability was assessed colorimetrically. Apoptosis was characterized by TUNEL assay, annexin V staining and caspase-3 activation. The mechanism(s) by which bilirubin induces apoptosis was investigated by Western blotting for cytochrome c release, assaying for caspase-8 and caspase-9 activation and for mitochondrial depolarization by JC-1 staining. The direct effect of bilirubin on the membrane potential of isolated mitochondria was evaluated using light-scattering and fluorescence techniques. Bilirubin decreased the viability of all colon cancer cell lines tested in a dose-dependent manner. Cells exhibited substantial apoptosis when exposed to bilirubin concentrations ranging 0-50 microM, as demonstrated by an 8- to 10-fold increase in TUNEL and annexin V staining and in caspase-3 activity. Bilirubin treatment evokes specific activation of caspase-9, enhances cytochrome c release into the cytoplasm and triggers the mitochondrial permeability transition in colon cancer monolayers. Additionally, bilirubin directly induces the depolarization of isolated rat liver mitochondria, an effect that is not inhibited by cyclosporin A. Bilirubin stimulates apoptosis of colon adenocarcinoma cells in vitro through activation of the mitochondrial pathway, apparently by directly dissipating mitochondrial membrane potential. As this effect is triggered at concentrations normally present in the intestinal lumen, we postulate a physiologic role for bilirubin in modulating colon tumorigenesis.

Role of UGT1A1 mutation in fasting hyperbilirubinemia

BACKGROUND AND AIM

Low-grade fasting hyperbilirubinemia is a common observation in healthy subjects (HS), whereas high-grade fasting hyperbilirubinemia is believed to be a characteristic finding of Gilbert's syndrome. This study was undertaken to assess the role of mutation in bilirubin UDP- glycosyltransferase gene (UGT1A1) on fasting hyperbilirubinemia.

METHODS

Analysis of UGT1A1 and a caloric restriction test (400 kcal for 24 h) were performed in 56 healthy subjects (25 males, 31 females), and 28 patients with Gilbert's syndrome (18 males, 10 females). There were 29 healthy subjects with no mutation in UGT1A1, and 27 healthy subjects and 26 Gilbert's syndrome patients with mutations in the coding and/or promoter (TATA box) regions of UGT1A1.

RESULTS

The mean increment of serum bilirubin (DeltaSB) was 7.6 micromol/L [corrected] (males) and 4.1 micromol/L (females) in subjects with no UGT1A1 mutation. Subjects with mutation in UGT1A1 showed higher levels of DeltaSB than individuals without mutation. Among healthy subjects, gender difference in DeltaSB values was observed only in individuals with the wild type of UGT1A1, but not in those with mutations in this gene.

CONCLUSION

The results of the present study suggest that UGT1A1 mutation has a role in the development of high-grade fasting hyperbilirubinemia after caloric restriction.

The utility of rifampin in diagnosing Gilbert's syndrome

OBJECTIVE

The aim of this study was to evaluate the effect of rifampin (the "rifampin test") on serum bilirubin in patients with and without Gilbert's syndrome.

METHODS

We conducted a clinical trial in which the effect of rifampin on serum bilirubin level in 15 patients with Gilbert's syndrome was compared with 10 patients without Gilbert's syndrome (controls) in a General Internal Medicine/Primary Care clinic of a Veterans Affairs medical center. Each participant underwent a "rifampin test," i.e., bilirubin measurement at baseline and 2, 4, and 6 h after the administration of 900 mg of rifampin. Measurements included complete blood count, blood chemistry including liver panel tests (ALP, AST, LDH, and albumin) along with total serum bilirubin levels. Ten patients with Gilbert's and nine control patients had haptoglobin level measured at baseline and 6 h after the administration of rifampin.

RESULTS

While fasting, the mean rise in total serum bilirubin at 2, 4, and 6 h after the administration of rifampin, respectively, was 0.5, 0.7, and 0.7 mg/dl (analysis of variance, p < 0.001) in control patients and 0.6, 1.0, and 1.1 mg/dl (p < 0.001) in the study patients. In 15 fed subjects (six control and nine study), the mean rise in total serum bilirubin at 2, 4, and 6 h, respectively, was 0.3, 0.5, and 0.6 mg/dl (p < 0.001) in controls and 0.5, 1.0, and 1.2 mg/dl (p < 0.001) in study subjects. In the fasting state, rise in total serum bilirubin to >1.9 mg/dl distinguished patients with Gilbert's syndrome from those without at 2, 4, and 6 h (sensitivity 100%, 93%, and 93%; specificity 100%, 100%, and 100% at 2, 4, and 6 h, respectively). In the nonfasting state, rise in total serum bilirubin to > 1.5 mg/dl at 4 and 6 h after rifampin administration distinguished the two groups (sensitivity 90% and 100%; specificity 100% and 100%, respectively).

CONCLUSIONS

Rifampin increases total serum bilirubin levels in patients with and without Gilbert's syndrome. On fasting for 12 to 24 h, an absolute increase of bilirubin to >1.9 mg/dl 2 to 6 h after the administration of 900 mg of rifampin distinguishes patients with Gilbert's syndrome from those without it. In the nonfasting state, an increase in total serum bilirubin to > 1.5 mg/dl 4 to 6 h after the administration of rifampin distinguishes persons with Gilbert's syndrome from those without it.

Donor liver uridine diphosphate (UDP)-glucuronosyltransferase-1A1 deficiency causing Gilbert's syndrome in liver transplant recipients

BACKGROUND

Uridine diphosphate-glucuronosyltransferase-1A1 deficiency, causing Gilbert's syndrome, has been attributed to two extra (TA) bases in the TATAA-box of the promoter region of its gene, where the A(TA)6TAA allele corresponds to the normal gene and A(TA)7TAA corresponds to a gene with reduced expression. Our aim was to determine whether isolated hyperbilirubinemia in liver transplant recipients was due to Gilbert's syndrome acquired through the liver allograft.

METHODS

From 305 patients followed in our Liver Transplant Clinic, five patients with isolated unconjugated hyperbilirubinemia in the absence of hemolysis, recurrent viral hepatitis, and biliary tract pathology were identified; 10 other post-orthotopic liver transplantion patients with normal liver chemistry tests were randomly selected as a control group. DNA was extracted from paraffin-embedded liver allograft tissue and peripheral lymphocytes and was genotyped for the TA repeat at the uridine diphosphate glucononosyltransferase-lA1 promoter region by polymerase chain reaction and acrylamide gel electrophoresis. Homozygosity for the (TA)7 allele was considered diagnostic of Gilbert's syndrome.

RESULTS

The mean serum total bilirubin level of the study patients was 2.28 mg/dl (range 1.8-3.0), consisting predominantly of the unconjugated form; that of the control patients was 0.76 mg/dl (range 0.4-1.1). The liver tissue from all five patients in the study group possessed the homozygous A(TA)7TAA genotype that was not observed in their lymphocytes. None of the liver tissue from the control patients demonstrated homozygosity for the A(TA)7TAA allele.

CONCLUSION

Uridine diphosphate-glucuronosyltransferase-1A1 deficiency, causing Gilbert's syndrome, may be carried by the donor liver and present with isolated unconjugated hyperbilirubinemia in liver transplant recipients.

Drug-mediated toxicity caused by genetic deficiency of UDP-glucuronosyltransferases

Human gene families encoding UDP-Glucuronosyltransferases (UGTs) have been identified and partially characterised. This family of enzymes catalysed the glucuronidation of drugs, xenobiotics and endobiotics. Genetic mutations and polymorphisms have been identified in several UGT genes and examples should be anticipated in all UGT genes. A common genetic defect in the TATA box promoter of the UGT1A1 gene is associated with Gilbert's Syndrome (GS) causing mild hyperbilirubinaemia. Recently, adverse effects of anticancer agents have been observed in Gilbert's patients due to reduced drug or bilirubin glucuronidation.

Molecular genetic basis of Gilbert's syndrome

Gilbert's syndrome, an hereditary, chronic, mild, unconjugated hyperbilirubinaemia resulting from impaired hepatic bilirubin clearance and otherwise normal liver function, is arguably the most common syndrome known in humans. Recent molecular genetic studies have determined that the clinical phenotype can be described by a dinucleotide polymorphism in the TATA box promoter of the bilirubin uridine diphosphate-glucuronosyltransferase (UGT-1A1) gene, most frequently (TA)7TAA, affecting up to 36% of Africans, but only 3% of Asians. However, a second common heterozygous mutation in the coding exon 1 of the UGT-1A1 gene (G71R) can also cause the Gilbert's phenotype in Japanese and Asians. The clinical phenotype may not be apparent as frequently as the determined genotype, due to environmental factors such as alcohol-induced hepatic bilirubin glucuronidation, reducing serum bilirubin levels and causing a latent condition. Gilbert's disease is a contributory factor of prolonged neonatal jaundice in breast-fed infants and may precipitate jaundice when coinherited with other disorders of haem metabolism. The genetic variation described as Gilbert's syndrome may lead to pharmacological variation in drug glucuronidation and unexpected toxicity from therapeutic agents.

Asymptomatic jaundice after fasting: a diagnostic dilemma

An 18-year-old female with asymptomatic jaundice presented to the emergency department after fasting. She was referred to the regional medical center for evaluation and treatment. The diagnosis of Gilbert's syndrome was made by fractionation of serum unconjugated and conjugated bilirubin fraction by alkaline methanolysis, followed by thin-layer chromatography and analysis of fasting-state levels of cholyl conjugated bile acids. Methods for diagnosing this disorder are discussed.

Persistent unconjugated hyperbilirubinemia after liver transplantation due to an abnormal bilirubin UDP-glucuronosyltransferase gene promoter sequence in the donor

BACKGROUND/AIMS

Gilbert's syndrome is genetically characterized by an extra TA element in the TATAA-box of the promotor region upstream of the bilirubin UDP-glucuronosyltransferase (UGT1A) coding region (Bosma et al. N Engl J Med 1995; 333: 1171-5). Persistent unconjugated hyperbilirubinemia is occasionally observed in liver transplant recipients with an otherwise normal liver function. We postulate that these patients could have received a liver from a donor with the Gilbert's syndrome genotype. Therefore, we investigated the UGT1A-gene TATAA-box in DNA from liver graft donors of jaundiced and non-jaundiced recipients.

METHODS

DNA was obtained from stored donor lymphocytes and the number of TA elements in the TATAA-box of the UGT1A-gene promotor region was analyzed by polymerase chain-reaction.

RESULTS

We observed two liver transplant recipients with persistent unconjugated hyperbilirubinemia. They received liver grafts from donors who were homozygous for an abnormal A(TA)7TAA-box in the UGT1A-gene. Four of 10 non-jaundiced recipients received livers from donors who were homozygous for the normal A(TA)6TAA-box and six received livers from donors who were heterozygous with a normal A(TA)6TAA-box on one allele and a prolonged A(TA)7TAA-box on the other allele.

CONCLUSIONS

This study shows that liver graft recipients with persistent unconjugated hyperbilirubinemia may have received a liver from a donor with an abnormal TATAA-box in the bilirubin UGT1A-gene promotor region.

Genetic variation in bilirubin UPD-glucuronosyltransferase gene promoter and Gilbert's syndrome

BACKGROUND

The genetic basis of Gilbert's syndrome is ill-defined. This common mild hyperbilirubinaemia sometimes presents as an intermittent jaundice. A reduced hepatic bilirubin UPD- glucuronosyltransferase (UGT) is associated with this syndrome. We have examined variation in the gene encoding the UGT1*1 enzyme and serum bilirubin levels in a Scottish population.

METHODS

Blood was collected from 12 patients with confirmed or suspected Gilbert's syndrome, from 6 members of a family with 4 Gilbert members, and from 77 non-smoking, alcohol-free, drug-free volunteers recruited from the staff of a teaching hospital in Dundee. Polymerase chain reaction amplification was used to examine sequence variation of the promoter upstream of the UGT1*1 exon I. Genotypes were assigned as follows: 6/6 (homozygous for a common allele bearing the sequence [TA](6)TAA), 7/7 (homozygous for a rarer allele with the sequence [TA](7)TAA), and 6/7 (heterozygous with one of each allele).

FINDINGS

Individuals in the population with the 7/7 genotype had significantly higher bilirubin concentrations than those who had the 6/7 or 6/6 genotype. 14 volunteers underwent a 24 h fasting test to see if they had Gilbert's syndrome, and all four positives had the 7/7 genotype. One confirmed Gilbert's patient, two recurrent jaundice patients (with suspected Gilbert's syndrome), and nine clinically diagnosed cases had the 7/7 genotype. Segregation of the 7/7 genotype with the Gilbert phenotype was also demonstrated in the family with four affected members. The frequency of the 7/7 genotype in this eastern Scottish population was 10-13%.

INTERPRETATION

In a healthy population there was an association between variation in bilirubin concentration and a mutation within the gene encoding the enzyme bilirubin UGT. This and other findings suggest the existence of a mild and a more severe form of Gilbert's syndrome, depending on whether the gene defect lies in the promoter sequence upstream of UGT1*I exon I, as here (mild), or in the coding sequence (severe) of the gene.