UGT1A1 gene linkage analysis: application of polymorphic markers rs4148326/rs4124874 in the Iranian population

Mutations in the UGT1A1 gene are responsible for hyperbilirubinemia syndromes including Crigler-Najjar type 1 and 2 and Gilbert syndrome. In view of the genetic heterogeneity and involvement of large numbers of the disease causing mutations, the application of polymorphic markers in the UGTA1 gene could be useful in molecular diagnosis of the disease.

In the present study, two polymorphic markers including rs4148326 and rs4124874 in the UGT1A1 gene region were characterized. The markers were selected using bioinformatics analysis of the UGT1A1 gene region and genotyped in 212 unrelated healthy individuals and 13 family trios in the Iranian population using Tetra-Primer ARMS PCR technique. The allele frequency and population status of the alleles were estimated using GENEPOP, FBAT, PowerMarker and Arlequin software.

The results indicated that in the case of rs4148326 marker, allele frequency for T and C allele was 66.04% and 33.96%, respectively. For rs4124874 marker, allele frequency for G and T alleles was 39.4% and 60.6%, respectively. The values of heterozygosity index for the markers examined were 64.1 for rs4148326 and 72.1 for rs4124874, respectively. The haplotype estimation analysis of the markers resulted in three informative haplotypes with frequencies ≥0.05. Moreover, the results suggested the presence of linkage disequilibrium between two markers.

Altogether, the data suggested that rs4148326 and rs4124874 could be introduced as informative markers for molecular diagnosis of Crigler-Najjar type 1 and 2 and Gilbert syndrome in the Iranian population.