Unconjugated hyperbilirubinemia in Anorexia nervosa is caused by uridine diphosphate glucuronosyltransferase 1A1 gene polymorphism

Background. Restricting anorexia nervosa (AN) is an eating disorder characterized with continuous strict dieting, exercising and amenorrhea in female patients. UDPglucuronosyltransferase 1A1 (UGT1A1) gene polymorphism 6TA→ 7TA in TATA box is associated with Gilbert's syndrome characterized with unconjugated hyperbilirubinemia. In healthy population incidence of Gilbert's syndrome (7/7 homozygous) is approximately 15% but unconjugated hyperbilirubinemia occurs only in 5-7%. Aim of this study was to determine frequencies of hyperbilirubinemia in restrictive type of AN and its association with UGT1A1 polymorphism. Patients and methods. In 48 consecutive patients (median age 14 years, interquartile range: 13-16 yrs ; F/M=45/3) with restrictive type of AN (BMI 15.45± ; 1.77) total, unconjugated bilirubin and UGT1A1 polymorphism were determined. Bilirubin concentrations were determined by the standard method. Polymorphism was detected using high-resolution electrophoresis of the PCR amplification products. Results. Unconjugated hyperbilirubinemia was present in 14 of 48 patients. Genotyping of UGT1A1 gene polymorphism showed results as follows: 8 of 48 (16.7%) were homozygous for 7 allele, 19 (39.6%) were heterozygous and 21 (43.7%) of total patients were wild types (6/6). Unconjugated hyperbilirubinemia was present in all homozygotes, 4/19 heterozygotes and even in 2/21wild type homozygotes. Conclusions. According to our results, frequencies and levels of hyperbilirubinemia depend on genotype but fully correlate only with homozygous 7/7 genotype. Chronic caloric deprivation provoke Gilbert's syndrome phenotype in all homozygous genotype, but also in some heterozygous and marginally in wild type genotype.