Problem: Recurrent pregnancy loss (RPL) affects 2-4% of couples, and remains largely unexplained. Recent studies have examined the role of cytokines in the maintenance of normal pregnancy, which is linked with an increased expression of Th2 cytokines. Overexpression of Th1 cytokines is associated with RPL. Knowing that functional polymorphisms exist for certain cytokines, it has therefore been suggested that women with RPL may have a genetic predisposition to overexpress Th1 cytokines.
Method of study: The genes for interleukin-1 beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) carry functional gene polymorphisms. In both cases these are biallelic polymorphisms that can be detected by polymerase chain reaction followed by restriction fragment length polymorphism. The aim of this pilot study was to assess whether carriage of the rarer alleles (TNF*2 and IL-1B*2) could act as independent risk factors in recurrent miscarriage.
Results: We found an increased incidence in the carriage of TNF*2, more pronounced in those women with two or more miscarriages. Carriage of the IL-1B*2 either alone or in association with TNF*2 was not associated with recurrent miscarriage.
Conclusion: There may be a role for these cytokine gene polymorphisms in RPL.