Rapid detection of the UGT1A1 single nucleotide polymorphism G211A using real-time PCR with Taqman minor groove binder probes

The UGT1A1 Taqman MGB probe single nucleotide polymorphism (SNP) genotyping assay was developed to detect nucleotide 211 of the UDP-glucoronocyltransferase 1A1 (UGT1A1) gene. Defects in this enzyme interfere with process of conjugation of bilirubin and cause unconjugated hyperbilirubinemia. Variation at nucleotide 211 in the coding region of the UGT1A1 gene has been shown to be prevalent in Japanese and Chinese. Using an ABI sequence detection system (SDS) 7000, an allele-specific real-time PCR-based genotyping method was established to detect nucleotide G211A. Cord blood from 125 infants without hyperbilirubinemia (controls) were compared with cord blood from 74 infants (cases) with severe hyperbilirubinemia (total serum bilirubin > 300 micromol/L). Homozygous variation of the UGT1A1 gene at nucleotide 211(A/A) is significantly more common in cases (14.9%) than in controls (0.8%) (P<0.001). Direct sequencing from 20 randomly selected samples showed eight samples with homozygous wild type, seven with homozygous variant, and five samples were heterozygous. The result from this assay was in complete concordance with the DNA sequencing result and clearly discriminate wild-type (G/G), homozygous variant (A/A), and heterozygous (G/A). This assay is rapid and robust for screening of SNP G211A to determine if this polymorphism plays a role in causing severe neonatal jaundice in the local context.