Annexin A5 is a natural anticoagulant assumed to have thrombomodulary functions as it shields phospholipid layers from coagulation complexes. It was recently shown that the M2 haplotype within the annexin A5 gene (ANXA5) promoter reduces the transcriptional activity of the gene. In a previous report, the M2 haplotype was found to be associated with pregnancy-related venous thrombosis (VT).
To investigate whether the M1 or M2 haplotypes or other genetic variations in ANXA5 are associated with pregnancy-related VT.
We investigated samples from 313 cases and 353 controls included in the VIP study, which is a case-control study of pregnancy-related VT. We analyzed tag single nucleotide polymorphisms (SNPs) selected from the CEU population (Utah Residents with Northern and Western European Ancestry) of HapMap and the M1 and the M2 haplotypes of the promoter. Odds ratios for VT were calculated for each haplotype with the wild type as the reference and for each tag SNP with the most common genotype as reference.
We did not find any association between genetic variants in ANXA5 and the risk of pregnancy related VT, but some of the genetic variants were not in Hardy-Weinberg equilibrium.
Neither the M1/M2 haplotypes nor the tag SNPs in ANXA5 were convincingly associated with pregnancy related VT, but other studies in this field are needed.