Annexin A5 (ANXA5) M2 Promoter Haplotype and Plasma Annexin A5 Level in Iraqi Women with Unexplained Recurrent Pregnancy Loss

Abstract

Unexplained recurrent pregnancy loss (uRPL) leaves many couples without a cause or a clear plan. Annexin A5 (ANXA5) lines the villous surface of the placenta as an anticoagulant shield, and the M2 haplotype of its promoter lowers gene expression. Data from Iraq are lacking. In this case–control study we enrolled 100 women with uRPL and 100 parous controls without pregnancy loss. The M2 haplotype was typed by PCR and Sanger sequencing of the ANXA5 core promoter, and plasma ANXA5 was measured by sandwich ELISA. Genotypes in both groups were in Hardy–Weinberg equilibrium. M2 carriers made up 32% of patients and 14% of controls (M2 allele frequency 0.190 vs 0.075). Carriage raised the odds of uRPL under the dominant model (OR 2.89, 95% CI 1.43–5.84) and the allelic model (OR 2.89, 95% CI 1.53–5.45). The effect held after adjustment for age and body mass index (adjusted OR 2.86, 95% CI 1.40–5.84) but was attenuated when plasma ANXA5 was added to the model (OR 1.30, p = 0.534), consistent with partial mediation. Plasma ANXA5 was lower in patients than in controls (1.82 ± 0.61 vs 2.64 ± 0.72 ng/mL, p < 0.001). Within patients it fell stepwise from N/N to M2/N to M2/M2 women and correlated inversely with the number of losses (r = −0.38). A cut-off of ≤2.10 ng/mL separated patients from controls with an area under the curve of 0.81, a sensitivity of 73% and a specificity of 78%. Maternal M2 carriage and low plasma ANXA5 appear to mark a thrombotic subgroup of uRPL in Iraqi women, and both deserve testing in larger prospective cohorts.