Prevalence of uridine glucuronosyl transferase 1A1 (UGT1A1) mutations in Malay neonates with severe jaundice

A number of genetic risk factors have been implicated in the development of neonatal severe hyperbilirubinaemia. This includes mutations in the uridine glucoronosyl transferase 1A1 (UGT1A1) gene which is responsible for unconjugated hyperbilirubinemia in Gilbert's Syndrome. We studied the prevalence of UGT1A1 gene mutations in a group of Malay neonates to determine whether they are risk factors to severe neonatal jaundice. One hundred and twenty-five Malay neonates with severe hyperbilirubinemia were studied. Ninety-eight infants without severe hyperbilirubinaemia were randomly selected from healthy Malay term infants (controls). DNA from EDTA cord blood samples were examined for UGT1A1 mutations nt211G > A and nt247T > C using established Taqman SNP genotyping assays and the UGT1A1*28 variant was detected by the Agilent 2100 bioanalyzer. All samples were also screened for common Malay G6PD variants using established techniques. The frequency of UGT1A1 211G > A mutation is significantly higher in the severely hyperbilirubinemic group (13%) than the control group (4%; p = 0.015) and all the positive cases were heterozygous for the mutation. There was no significant difference in the frequency of UGT1A1*28 mutation between the severely hyperbilirubinemic (3.5%) and the control group (0.01%; p = 0.09). None of the neonates in both groups carried the nt247 T > C mutation. The prevalence of G6PD mutation was significantly higher in the severely jaundiced group than control (9% vs 4%; p = 0.04). In conclusion, nt 211 G > A alleles constitute at least 12% of UGT1A1 mutations underlying unconjugated hyperbilirubinemia and appears to be a significant independent risk factor associated with severe neonatal hyperbilirubinemia in the Malay newborns.