Compound heterozygous UGT1A1*28 and UGT1A1*6 or single homozygous UGT1A1*28 are major genotypes associated with Gilbert ? s syndrome in Chinese Han people

Gilbert?s syndrome (GS) is a mild condition characterized by periods of hyperbilirubinemia, which results in variations in the UDP-glucuronosyltransferase 1 (UGT1A1) gene. Variant genotypes of UGT1A1 vary in different populations in the world. The present study aimed to determine the genotype of the UGT1A1 promoter and exon that are related to the serum total bilirubin (STB) level in the Chinese Han population. A total of 120 individuals diagnosed with GS (GS group) and 120 healthy individuals (non-GS group) were enrolled. Routine blood, liver function tests, and antibodies associated with autoimmune liver diseases were assessed. Blood samples were collected for DNA purification. Sequencing of the UGT1A1 promoter and exons was conducted for post segment amplification by PCR. Compound heterozygous UGT1A1*28 and UGT1A1*6 (25/120, 20.83%), single homozygous UGT1A1*28 (24/120, 20.00%) and single heterozygous UGT1A1*6 (18/120, 15.00%) were the most frequent genotypes in the GS group. However, single heterozygous UGT1A1*6 (30/120, 25.00%) and single heterozygous UGT1A1*28 (19/120, 15.83%) were the most frequent genotypes in the non-GS group. Further, the frequencies of single homozygous UGT1A1*28, compound heterozygous UGT1A1*28 and UGT1A1*6, and compound heterozygous UGT1A1*28, UGT1A1*6 and UGT1A1*27 were significantly higher in the GS group than those in the non-GS group. The STB levels of GS patients with the homozygous UGT1A1*28 genotype were remarkably higher than those of patients with other genotypes. Homozygous UGT1A1*28 and heterozygous UGT1A1*6 variants were associated with the highest and lowest risks of hyperbilirubinemia, respectively. Our study revealed that compound heterozygous UGT1A1*28 and UGT1A1*6, or single homozygous UGT1A1*28 are major genotypes associated with GS in Chinese Han people. These findings might facilitate the precise genomic diagnosis of Gilbert?s syndrome.