ADRB2 Gene Polymorphism and Tocolytic Response to Hexoprenaline in Pregnant Russian Women with Threatened Preterm Labor

Background: Hexoprenaline, a widely used tocolytic, is a β2 adrenergic receptor agonist that when administered relaxes the smooth muscles in the uterus and cervix. The Gly16Arg polymorphism in the ADRB2 gene is known to be associated with the risk of threatened preterm labor (TPL). Moreover, the Gly16Arg and Gln27Glu polymorphisms that form haplotypes can modulate receptor function, changing the pharmacological response to β2 agonists. Aims: This study aimed to investigate the effects of ADRB2 gene polymorphisms on TPL and the response to tocolytic treatment with hexoprenaline in pregnant Russian women. Materials and Methods: This prospective case–control study on tocolytic therapy included 60 pregnant women with TPL who received tocolytic treatment with hexoprenaline and a control group consisting of 60 pregnant women not at risk of TPL. A polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) analysis was conducted to determine the frequencies of Gly16Arg and Gln27Glu polymorphisms in the ADRB2 gene in both groups. These data were compared with the TPL status and the tocolytic effect of hexoprenaline. Results: It is shown that carrying the ADRB2 16Arg allele is associated with decreased incidence of preterm birth (PTB), while the 16Gly/Gly genotype is related to an increased risk of PTB (OR = 2.444; CI95% = 1.167–5.121). The allele frequencies of the Gly16Arg and Gln27Glu polymorphisms in the ADRB2 gene in healthy pregnant Russian women are consistent with those in the European population. Due to small subgroup sizes, tocolytic outcomes are presented descriptively without a powered statistical analysis. Conclusions: These findings suggest a preliminary association between the ADRB2 16Gly allele and the 16Gly/Gly genotype with an increased risk of PTB in pregnant Russian women. While carriers of the 16Arg allele may have a decreased risk, these pharmacogenetic insights require independent validation in larger cohorts before clinical recommendations can be formulated.