ABSTRACT Gilbert syndrome is a common autosomal dominant hereditary condition with incomplete penetrance and characterized by intermittent unconjugated hyperbilirubinemia in the absence of hepatocellular disease or hemolysis. In patients with Gilbert syndrome, uridine diphosphate-glucuronyl transferase activity is reduced to 30% of the normal, resulting in indirect hyperbilirubinemia. In its typical form, hyperbilirubinemia is first noticed as intermittent mild jaundice in adolescence. However, Gilbert syndrome in combination with other prevailing conditions such as breast feeding, G-6-PD deficiency, thalassemia, spherocytosis, or cystic fibrosis may potentiate severe hyperbilirubinemia and/or cholelithiasis. It may also reduce plasma oxidation, and it may also affect drug metabolism. Although in general the diagnosis of the syndrome is one of exclusion, molecular genetic tests can now be performed when there is a diagnostic problem. The most common genotype of Gilbert syndrome is the homozygous polymorphism A(TA)7TAA in the promoter of the gene for UDP-glucuronosyltransferase 1A1 (UGT1A1), which is a TA insertion into the promoter designated UGT1A1*28. No specific management is necessary as Gilbert syndrome is a benign condition. CONCLUSION: Gilbert genotype should be kept in the clinician's mind, at least as a contributor factor, in cases with unexplained indirect hyperbilirubinemia.
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ABSTRACT: Gilbert syndrome is the most common inherited disorder of bilirubin glucuronidation. It is characterized by intermittent episodes of jaundice in the absence of hepatocellular disease or hemolysis. Hereditary spherocytosis is the most common inherited hemolytic anemia and is characterized by spherical, osmotically fragile erythrocytes that are selectively trapped by the spleen. The patients have variable degrees of anemia, jaundice, and splenomegaly. Hereditary spherocytosis usually leads to mild-to-moderate elevation of serum bilirubin levels. Severe hyperbilirubinemia compared with the degree of hemolysis should be lead to suspicion of additional clinical conditions such as Gilbert syndrome or thalassemia. We present the case of a 12-year-old boy with extreme jaundice and nausea. The diagnosis of hereditary spherocytosis was confirmed by osmotic fragility test results and that of Gilbert syndrome by genetic analysis findings.12/2014; 17(4):266-9. DOI:10.5223/pghn.2014.17.4.266
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ABSTRACT: Backgrounds and Aims: UDP-glucuronosyltransferase 1 A1 (UGT1A1) is an enzyme that transforms small lipophilic molecules into water-soluble and excretable metabolites. UGT1A1 polymorphisms contribute to hyperbilirubinemia. This study quantitatively associated UGT1A1 variants in patients with hyperbilirubinemia and healthy subjects. Methods:A total of 104 individuals with hyperbilirubinemia and 105 healthy controls were enrolled for genotyping and DNA sequencing UGT1A1 sequence variants, including the Phenobarbital Response enhancer module (PBREM) region, the promoter region (TATA box), and the 5 exons for quantitative association with hyperbilirubinemia. Results: Eleven UGT1A1 variants were revealed in the case and control subjects, four of which were novel coding variants. A variant of PBREM (UGT1A1*60) was found in 47.6% of the patients, a TA repeat motif in the 5-primer promoter region [A(TA)(7)TAA,UGT1A1*28] was found in 27.9% of the patients, and p.G71R (UGT1A1*6) was in 33.2% of the patients. For the healthy controls, the frequency of UGT1A1*60, UGT1A1*28 and UGT1A1*6 was 26.7%, 9.0% and 15.7%, respectively. Homozygous UGT1A1*28 and homozygous UGT1A1*6 were significantly associated with the risk of adult hyperbilirubinemia, with an odds ratio (OR) of 17.79 (95% CIs, 2.11-133.61) and 14.93 (95% CIs, 1.83-121.88), respectively. Quantitative analysis showed that sense mutation (including UGT1A1*6) and UGT1A1*28/*28, but not UGT1A1*60/*60 or UGT1A1*1/*28, was associated with increased serum total bilirubin (TB) levels. High linkage disequilibrium occurred between UGT1A1*60 and UGT1A1*28 (D' = 0.964, r(2) = 0345). Conclusions: This study identified four novel UGT1A1 coding variants, some of which were associated with increased serum TB levels. A quantitative approach to evaluate adult hyperbilirubinemia provides a more vigorous framework for better understanding of adult hyperbilirubinemia genetics.Gene 09/2014; 552(1). DOI:10.1016/j.gene.2014.09.009 · 2.08 Impact Factor
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ABSTRACT: Most Taiwanese patients with hyper-bilirubinemia have genetic abnormalities in the uridine diphosphoglucuronate-glucuronosyltransferase 1A1 (UGT1A1) gene beyond the variants in the TATA box upstream of UGT1A1 associated with Gilbert's syndrome. To investigate the role of UGT1A1 in the pathogenesis of indirect hyper-bilirubinemia, we prospectively studied 97 consecutive patients with indirect hyper-bilirubinemia for genotypes of promoter [(TA)6TAA6, (TA)7TAA7] and coding region [nucleotide (nt)-211, nt-686, nt-1,091 and nt-1,456] of UGT1A1. Thirty-six of the patients (45.6%) were found to have Gilbert's syndrome with 7/7 genotype; among them, 14 also carried variants at nt-686. Forty-two patients (43.3%) had the 6/7 genotype; among them, 36 patients were found to have one or more variants in the coding region. Patients with higher serum total bilirubin are associated with higher likelihood of carrying Gilbert's syndrome genotype: 60.0% (P=0.007) patients with serum total bilirubin level ≥2.5 mg/dL carried the Gilbert's syndrome genotype, while only 23.9% of patients with serum total bilirubin level <2.5 mg/dL carry the same genotype (P=0.0006). Forty-one of the 61 non-Gilbert's patients had one homogenous variants or two or more heterozygous variants in UGT1A1. Further studies are necessary to confirm the role of one homo-zygous variant or two or more hetero-zygous variants in UGT1A1 gene as factors for indirect hyper-bilirubinemia.