title: Body fat percentage is a major determinant of total bilirubin independently of UGT1A1*28 polymorphism in young obese.
abstract: OBJECTIVE
  Bilirubin has potential antioxidant and anti-inflammatory properties. The UGT1A1*28 polymorphism (TA repeats in the promoter region) is a major determinant of bilirubin levels and recent evidence suggests that raised adiposity may also be a contributing factor. We aimed to study the interaction between UGT1A1 polymorphism, hematological and anthropometric variables with total bilirubin levels in young individuals.
  
  
  METHODS
  350 obese (mean age of 11.6 years; 52% females) and 79 controls (mean age of 10.5 years; 59% females) were included. Total bilirubin and C-reactive protein (CRP) plasma levels, hemogram, anthropometric data and UGT1A1 polymorphism were determined. In a subgroup of 74 obese and 40 controls body composition was analyzed by dual-energy X-ray absorptiometry.
  
  
  RESULTS
  The UGT1A1 genotype frequencies were 49.9%, 42.7% and 7.5% for 6/6, 6/7 and 7/7 genotypes, respectively. Patients with 7/7 genotype presented the highest total bilirubin levels, followed by 6/7 and 6/6 genotypes. Compared to controls, obese patients presented higher erythrocyte count, hematocrit, hemoglobin and CRP levels, but no differences in bilirubin or in UGT1A1 genotype distribution. Body fat percentage was inversely correlated with bilirubin in obese patients but not in controls. This inverse association was observed either in 6/7 or 6/6 genotype obese patients. UGT1A1 polymorphism and body fat percentage were the main factors affecting bilirubin levels within obese patients (linear regression analysis).
  
  
  CONCLUSIONS
  In obese children and adolescents, body fat composition and UGT1A1 polymorphism are independent determinants of total bilirubin levels. Obese individuals with 6/6 UGT1A1 genotype and higher body fat mass may benefit from a closer clinical follow-up.
authors.affiliation: Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Belo
authors.affiliation: Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
authors.forename: Henrique
authors.initials: H
authors.lastname: Nascimento
authors.affiliation: Institute for Biomedical Imaging and Life Science (IBILI), Faculdade de Medicina, Universidade de Coimbra, Coimbra, Portugal.
authors.forename: Michaela
authors.initials: M
authors.lastname: Kohlova
authors.affiliation: Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
authors.forename: Elsa
authors.initials: E
authors.lastname: Bronze-da-Rocha
authors.affiliation: Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Institute for Biomedical Imaging and Life Science (IBILI), Faculdade de Medicina, Universidade de Coimbra, Coimbra, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Fernandes
authors.affiliation: Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
authors.forename: Elísio
authors.initials: E
authors.lastname: Costa
authors.affiliation: Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Catarino
authors.affiliation: Centro de Investigação em Actividade Física, Saúde e Lazer (CIAFEL), Faculdade de Desporto, Universidade do Porto, Porto, Portugal; Instituto Universitário da Maia (ISMAI), Maia, Portugal.
authors.forename: Luísa
authors.initials: L
authors.lastname: Aires
authors.affiliation: Departamento da Infância e Adolescência/Serviço de Pediatria do Centro Hospitalar do Porto, Porto, Portugal.
authors.forename: Helena Ferreira
authors.initials: HF
authors.lastname: Mansilha
authors.affiliation: Centro de Investigação em Ciências da Saúde, Universidade da Beira Interior, Covilhã, Portugal.
authors.forename: Petronila
authors.initials: P
authors.lastname: Rocha-Pereira
authors.affiliation: Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal; Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Quintanilha
authors.affiliation: Centro da Criança e do Adolescente. Hospital CUF Porto, Center for Health Technology and Services Research (CINTESIS), Faculdade de Medicina, Universidade do Porto, Porto, Portugal.
authors.forename: Carla
authors.initials: C
authors.lastname: Rêgo
authors.affiliation: Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
authors.forename: Alice
authors.initials: A
authors.lastname: Santos-Silva
mesh_terms: D050154:Adiposity / Q000235:genetics*; D000293:Adolescent; D000483:Alleles; D001663:Bilirubin / Q000097:blood / Q000378:metabolism*; D002097:C-Reactive Protein / Q000378:metabolism; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D005787:Gene Frequency; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D005838:Genotype; D014453:Glucuronosyltransferase / Q000235:genetics*; D006801:Humans; D008297:Male; D009765:Obesity / Q000097:blood / Q000235:genetics* / Q000378:metabolism*; D011110:Polymorphism, Genetic; D000099148:UGT1A1 Enzyme
chemical_list: D001663:Bilirubin; D002097:C-Reactive Protein; D014453:Glucuronosyltransferase; D000099148:UGT1A1 Enzyme