Multiple variants in UGT1A1 gene are factors to develop indirect hyper-bilirubinemia

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.

Application of pharmacogenetics in oncology

The term "pharmacogenetics" is used to describe the study of variability in drug response due to heredity. It is associated with "gene - drug interactions". Later on, the term "pharmacogenomics" has been introduced and it comprises all genes in the genome that can define drug response. The application of pharmacogenetics in oncology is of a great significance because of the narrow therapeutic index of chemotherapeutic drugs and the risk for life-threatening adverse effects. Many cancer genomics studies have been focused on the acquired, somatic mutations; however, increasing evidence shows that inherited germline genetic variations play a key role in cancer risk and treatment outcome. The aim of this review is to summarize the state of pharmacogenomics in oncology, focusing only on germline mutations. Genetic polymorphisms can be found in the genes that code for the metabolic enzymes and cellular targets for most of the chemotherapy drugs. Nevertheless, predicting treatment outcome is still not possible for the majority of regimens. In this review, we discuss the most comprehensively studied drug-gene pairs - present knowledge and current limitations. However, further studies in larger groups of cancer patients are necessary to be conducted with precise validation of pharmacogenetic biomarkers before these markers could be routinely applied in clinical diagnosis and treatment.

The Association between Prolonged Jaundice and TATA Box Dinucleotide Repeats in Gilbert's Syndrome

Introduction

Jaundice is a common condition during the neonatal period. Prolonged jaundice occurs in a large number of breastfed infants, considering the impact of genetic factors on the incidence of jaundice.

Aim

To determine the association between prolonged jaundice and TATA box dinucleotide repeats in Gilbert's Syndrome (GS).

Materials and Methods

In this case-control study, the case group consisted of 51 neonates with jaundice, aged more than two weeks with indirect bilirubin level higher than 10 mg/dl. Acute diseases, mother's use of phenobarbital and other medications were the exclusion criteria. The control group consisted of 54 newborns without jaundice. The two groups were matched in terms of age and sex. TATA box polymorphisms in the promoter region of UGT1A1 gene were evaluated using Polymerase Chain Reaction (PCR) in order to determine TATA box dinucleotide repeats.

Results

Overall, 64.7% and 50% of subjects in the case and control groups were male, respectively (p=0.168). The mean age of neonates in the case and control groups was 20.1±7.1days and 18.8±4.1 days, respectively. The distribution of Gilbert genome was not significantly different between the two groups. In the case group, 13.7% of the subjects were homozygous, 37.3% were heterozygous and 49% were normal. In the control group, 7.4% of the participants were homozygous, 35.2% were heterozygous and 57.4% were normal.

Conclusion

The results of this study showed an association between TATA box polymorphism and prolonged jaundice in neonates which revealed that TATA box polymorphism is an important risk to increase and extend icterus.