Glutathione S-transferase (GST) is a polymorphic supergene family of detoxification enzymes that are involved in the metabolism of numerous diseases. Several allelic variants of GSTs show impaired enzyme activity and are suspected to increase the susceptibility to diseases. Bilirubin is bound efficiently by GST members. The most commonly expressed gene in the liver is GSTM1, and GSTT1 is expressed predominantly in the liver and kidneys. To ascertain the relationship between GST and neonatal hyperbilirubinemia, the distribution of the polymorphisms of GSTT1 and GSTM1 were investigated in this study.

Genomic DNA was isolated from 88 patients and 186 healthy controls. The genotypes were analyzed by polymerase chain reaction (PCR).

The overall frequency of the GSTM1 null was lower in patients compared to controls ( P =0.0187, Odds ratio (OR) =0.52, 95% confidence interval (CI), 0.31-0.88). Also, the GSTT1 null was lower in patients compared to controls ( P =0.0014, OR=0.41, 95% CI=0.24-0.70). Moreover, the frequency of the null type of both, in the combination of GSTM1 and GSTT1, was significantly reduced in jaundiced patients ( P =0.0008, OR=0.31, 95% CI=0.17-0.61).

We hypothesized that GSTM1 and GSTT1 might be associated with neonatal hyperbilirubinemia. However, the GSTT1 and GSTM1 null type was reduced in patients. Therefore the null GSTT1, null GSTM1, and null type of both in the combination of GSTM1 and GSTT1 may be not a risk factor of neonatal jaundice.