Haptoglobin phenotype and risk of cervical neoplasia: A case-control study

BackgroundHaptoglobin is an acute-phase glycoprotein that influences host response to infections and tumours. The haptoglobin locus is polymorphic with 2 classes of alleles (Hp1 and Hp2) yielding 3 phenotypes: Hp1-1, Hp2-2, and Hp2-1 with structurally and functionally distinct protein products, suggesting that haptoglobin polymorphism may influence susceptibility to infections and cancers.MethodsWe examined the relation between haptoglobin phenotype and high-grade cervical intraepithelial neoplasia (CIN) in a hospital-based case-control study. Cases (n = 307) were women with biopsy-confirmed CIN-2 or CIN-3. Controls (n = 358) were a random sample of women with normal cytology. The PGMY polymerase chain reaction and reverse line blot methods were used for HPV detection and genotyping. Haptoglobin phenotype was determined by polyacrylamide gel electrophoresis.ResultsAmong controls, phenotype distribution corresponded to allele frequencies of 0.39 for Hp1 and 0.61 for Hp2 with no significant deviation from the Hardy–Weinberg equilibrium (p = 0.66). With all women included in the analysis, the Hp1-1 phenotype was associated with increased risk of CIN (OR contrasting Hp1-1 vs. Hp2-2 = 1.0; 95% CI: 0.6–1.5). However, in analyses restricted to HPV-positive participants, the Hp1-1 phenotype was associated with 2.7-fold (95% CI: 1.0–7.2) higher risk of CIN.ConclusionsIf confirmed, these findings indicate an increased risk of CIN among women with the Hp1-1 phenotype.