Genetic lesions in the UGT1A1 genes among Gilbert's syndrome patients from India

Influence of UGT1A1 promoter polymorphism, α-thalassemia and βs haplotype in bilirubin levels and cholelithiasis in a large sickle cell anemia cohort

Hyperbilirubinemia in patients with sickle cell anemia (SCA) as a result of enhanced erythrocyte destruction, lead to cholelithiasis development in a subset of patients. Evidence suggests that hyperbilirubinemia may be related to genetic variations, such as the UGT1A1 gene promoter polymorphism, which causes Gilbert syndrome (GS). Here, we aimed to determine the frequencies of UGT1A1 promoter alleles, alpha thalassemia, and β^S haplotypes and analyze their association with cholelithiasis and bilirubin levels. The UGT1A1 alleles, -3.7 kb alpha thalassemia deletion and β^S haplotypes were determined using DNA sequencing and PCR-based assays in 913 patients with SCA. The mean of total and unconjugated bilirubin and the frequency of cholelithiasis in GS patients were higher when compared to those without this condition, regardless of age (P < 0.05). Cumulative analysis demonstrated an early age-at-onset for cholelithiasis in GS genotypes (P < 0.05). Low fetal hemoglobin (HbF) levels and normal alpha thalassemia genotype were related to cholelithiasis development (P > 0.05). However, not cholelithiasis but total and unconjugated bilirubin levels were associated with β^S haplotype. These findings confirm in a large cohort that the UGT1A1 polymorphism influences cholelithiasis and hyperbilirubinemia in SCA. HbF and alpha thalassemia also appear as modulators for cholelithiasis risk.

Gilbert's Syndrome in Children with Unconjugated Hyperbilirubinemia - An Analysis of 170 Cases

There is limited literature on Gilbert's syndrome (GS) in children with persistent unconjugated hyperbilirubinemia from Indian subcontinent. All patients (< 18 y of age) with genetically confirmed GS were included, and their profile was analysed. A total of 170 subjects were confirmed as having GS as per genetic analysis (133 with homozygous and 37 with heterozygous status). Majority were diagnosed in the adolescent age group (mean age 13.6 y). The median serum total bilirubin (TB) levels were around 3.3 mg/dl with maximum levels reaching upto 18 mg/dl. Around 15% subjects had an associated condition including hematological or hepatobiliary disease amongst others. GS is an important but under-recognised cause of unexplained unconjugated hyperbilirubinemia in Indian pediatric subjects. It may co-exist with other hematological and hepatobiliary disorders, and complicate the clinical/laboratory picture. Extent of hyperbilirubinemia may fluctuate to levels much higher than what is usually described in current world literature.