Polymorphism of haptoglobin in patients with premature rupture of membrane

Purpose: To investigate whether allelic polymorphism of haptoglobin (Hp) is associated with premature rupture of membrane (PROM), the Hp phenotypes of pregnant women with PROM were analyzed. Patients and Methods: The Hp phenotypes of 221 pregnant Korean women (187 control and 34 PROM patients) were determined by benzidine/hydrogen peroxide staining, following native polyacrylamide gel electrophoresis of hemoglobin-mixed sera. The Hp allele frequencies were calculated from the data of Hp phenotypes, and overall association with PROM was evaluated using Pearson Chi-Square test. Results: The polymorphic distribution of the patients cohort who underwent a normal delivery (control group) was similar to that of healthy Koreans. In contrast, however, patients with PROM showed significantly higher occurrence of the Hp 1-1 phenotype than control group (23.5% vs 8.0%). Hp 2-2 phenotype was lower in PROM cohort (38.2%) than in the control group (48.7%). The Hp¹ allele frequency in PROM group was significantly higher than that in the control group (0.426 vs 0.297, p = 0.034) with odds ratio of 1.762 (95% CI: 1.038-2.991). Conclusion: These findings suggest that pregnant Korean women who possess Hp¹ allele (expressed as Hp 1-1 phenotype) have higher incidence of PROM than women with Hp² allele (expressed as Hp 2-2 phenotype). This is the first study that evaluated the significance of Hp polymorphism with respect to the development of PROM.