TNF-α-308 G/A POLYMORPHISM AS A GENETIC DETERMINANT OF SUSCEPTIBILITY TO HELICOBACTER PYLORI AND CRYPTOSPORIDIUM CO-INFECTION

Abstract

Tumour necrosis factor-alpha (TNF-α) is a key pro-inflammatory cytokine involved in host defence against gastrointestinal pathogens. This study investigated the association between the TNF-α −308 G>A (rs1800629) polymorphism and susceptibility to concurrent Helicobacter pylori and Cryptosporidium infection in an Iraqi population. A hospital-based case-control study included 100 unrelated Iraqi Arabs comprising 50 patients with confirmed co-infection and 50 healthy controls. Genotyping was performed using Tetra-Primer ARMS-PCR, and associations were analysed using logistic regression adjusted for age and sex. The control group conformed to Hardy-Weinberg equilibrium (p = 0.716). The AA genotype was significantly more frequent among co-infected patients than controls (28.0% vs. 4.0%; adjusted OR = 8.10, 95% CI: 2.95–22.24; p < 0.001), whereas the GA genotype showed no significant association. The A allele was associated with increased odds of co-infection (OR = 2.92, 95% CI: 1.52–5.60; p = 0.0008), and the recessive model demonstrated the strongest association (OR = 9.33; p < 0.001).

These findings provide novel evidence that the TNF-α −308 A allele is associated with increased odds of H. pylori and Cryptosporidium co-infection, highlighting the role of host genetic variation in polymicrobial gastrointestinal disease.