ASSOCIATION OF INTRON-2 VARIABLE NUMBERS OF AN 86-BP TANDEM REPEAT-POLYMORPHISMS OF INTERLEUKIN-1 RECEPTOR ANTAGONIST GENE AND IDIOPATHIC RECURRENT SPONTANEOUS ABORTION

Background: It has been proposed that abnormal modulation of inflammatory response is involved in the physiopathology of idiopathic recurrent spontaneous abortion (iRSA). Factors that may participate in this process include the genetic background such as carrying specific polymorphisms of genes with functional effects. Objective: The objective is to study the association between iRSA and the frequency of intron-2 variable number tandem repeat-polymorphisms of interleukin-1 receptor antagonist gene (IL1RN). Methods: We conducted a case-control study including 108 women with iRSA and 103 controls. Five allelic variants of IL1RN were determined by polymerase chain reaction (PCR) product length analysis. Results: The most frequent IL1RN allele in this population was IL1RN*1, which was present in 78% of cases and 94% of controls, and allele IL1RN*2, in 45 (20.8%) cases and 12 (5.8%) controls. Allele IL1RN*2 was significantly associated with iRSA (odds ratio = 4.28, 95% confidence interval 2.2-8.4; p = 0.000). Conclusion: Carrying allele IL1RN*2 had a strong association with iRSA in Mexican women. This polymorphism codifies for a low-function protein, which may allow for increased activity of IL-1 pro-inflammatory axis in iRSA.