Background: Circulating relaxin levels have repeatedly been associated with preterm birth (PTB). Our aim was to investigate if mothers carrying promoter single nucleotide polymorphisms (SNPs) in one of the three relaxin genes (RLN1, RLN2, RLN3) are predisposed for PTB.
Patients and methods: Maternal DNA from 80 preterm cases (40 very preterm births (24-34 weeks) and 40 moderate preterm (34-36 weeks) and 40 controls (term delivery)) nested in the Danish National Birth Cohort were examined for nine SNPs.
Results: Maternal homozygosity of the rarer allele in the relaxin 2 gene (RLN2, rs10115467 and rs4742076) had an increased risk of moderate PTB (odds ratio 4.1 [95% CI 1.4-12] and 8.8 [95% CI 1.03-75] respectively). Only rs10115467 remained significant after correction for multiple testing.
Conclusion: Women homozygous for prevalent SNPs in the RLN2 gene may have a genetic susceptibility for PTB.