International Journal of Gynecology and Obstetrics 77 (2002) 209–215 0020-7292/02/$ - see front matter  2002 International Federation of Gynecology and Obstetrics. Published by Elsevier Science B.V. All rights reserved. PII:S0020-7292 Ž 02 . 00035-8 Article Association of the Gln27Glu polymorphism of the beta-2- adrenergic receptor with preterm labor M. Ozkur *, F. Dogulu , A. Ozkur , B. Gokmen , S.S. Inaloz , A.S. Aynacioglu a, b c b d e Department of Pharmacology, Medical Faculty, Gaziantep University, Gaziantep, Turkey a Ministry of Health Ankara Education and Research Hospital Gynecology and Infertility Department, Cebeci, Ankara, Turkey b Department of Radiology, Medical Faculty, Gaziantep University, Gaziantep, Turkey c Department of Histology & Embryology, Medical Faculty, Gaziantep University, Gaziantep, Turkey d Department of Pharmacology, Medical Faculty, Pamukkale University, Denizli, Turkey e Received 19 November 2001; received in revised form 6 March 2002; accepted 6 March 2002 Abstract Objectives: To investigate a potential association between the beta-2-adrenergic receptor (B2AR) polymorphisms occurring at amino acid positions 16 (Arg16Gly) and 27 (Gln27Glu) and preterm labor. Methods: Eighty patients with preterm labor and 76 control subjects were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results: A significant association was found between Gln27Glu substitution and preterm labor (Ps0.001). The frequency of Gly16 and Glu27 alleles were found to be higher in patients than in control women (0.54 vs. 0.48 and 0.42 vs. 0.26, respectively), and the odds ratio for the occurrence of preterm labor was 2.14 (95% CI, 1.32–3.46; Ps0.002) for the Glu 27 allele. An early delivery was noted in 52.5% of patients. Conclusion: The Gln27Glu polymorphism of the B2AR gene may have a role in molecular pathogenesis of preterm labor. Glu27 allele in patients with preterm labor might be a risk factor for deliveries before 37 weeks of gestation.  2002 International Federation of Gynecology and Obstetrics. Published by Elsevier Science B.V. All rightsreserved. Keywords: Beta-2-adrenergic receptor; Polymorphism; Preterm labor 1. Introduction Preterm birth of less than 37 completed weeks of gestation occurs in 5–10% of all pregnancies w1x. It is the single largest cause of perinatal mortality and morbidity in non-anomalous infants in developed nations w2x. Preterm birth accounts for more than two-thirds of all singleton neonatal *Corresponding author. Tel.: q90-342-339-8501; fax: q90- 342-3601617. E-mail address: aozkur@hotmail.com (M. Ozkur). deaths excluding congenital malformations w3x. Preterm infants are at risk for specific diseases relating to the immaturity of various organ sys- tems, which increase with decreasing gestational age at delivery and sometimes require life long care w2,4x. Beta agonists have been used extensively for more than 30 years to inhibit uterine contractions for the prevention of preterm birth and have been shown to be effective in prolonging pregnancy for at least 48 h, long enough to allow maternal