Preterm birth is the leading cause of mortality and morbidity in infants. that the polymorphism of PLA2G4D rs4924618 may have a protective influence on the SPTB susceptibility in a Chinese population, supporting a role for genetics in the association between PG BTZ044 synthesis and preterm birth. fertilization (n=5), fetal anomaly (n=1) or uterine malformation (n=1) were excluded, resulting in 114 women having a spontaneous preterm birth (42 preterm labor and 72 preterm premature rupture of membranes) in the present study as the case group. In addition, 250 pregnant women, who delivered singleton term babies (38C41 weeks of gestation) and had no preeclampsia, eclampsia, placental abruption, placenta previa, haemolysis, elevated liver enzymes or low platelet count syndrome, were selected and included as the control group. Controls were frequency-matched to the cases by age within 3 years. The study was approved by the Institutional Review Board of GWCMC. Informed consent was obtained from all participants. SNP selection To select SNPs, the authors conducted a systematic literature review, assessing the evidence for the associations of PLA2G4C and PLA2G4D with SPTB. For the PLA2G4C gene, four SNPs had been reported to influence preterm birth risk in the US Hispanic or White populations (18). However, three of them (rs8110925, rs2307276 and rs11564620) were excluded due to the minor allele frequencies (MAF) reported in HapMap (http://hapmap.ncbi.nlm.nih.gov/) were <10% for Chinese subjects. Only rs1366442 in the intron region with a MAF of 13% was chosen ITM2A to ensure that an adequate number of individuals within the population would be carriers of the minor allele. For the PLA2G4D gene, published reports on polymorphisms of this gene and diseases are rare. The authors chose rs4924618 based on the following two reasons: i) a weak association between this SNP and schizophrenia was observed in a Chinese population (20), while schizophrenia was related to a higher risk of preterm birth (22,23); ii) this SNP is a non-synonymous SNP that is likely to alter the protein folding structure, suggesting that this SNP may have a functional effect. Genotyping Blood samples were stored at ?80C until laboratory use. Genomic DNA was extracted from cells isolated from 2 ml of blood samples using the Qiagen DNA Blood Mini kit (Qiagen, Inc., Valencia, CA, USA) according to the manufacturer’s instructions. Genotyping for PLA2G4C rs1366442 and PLA2G4D rs4924618 was performed by using a MassARRAY system (Sequenom, San Diego, CA, USA). A total BTZ044 of 20 samples (5.5% of total) were tested in duplicates to determine the quality of genotyping, and the concordance rates were 100%. DNA from 4 (1.1%) and 5 (1.4%) samples failed to be genotyped for PLA2G4C rs1366442 and PLA2G4D rs4924618. Covariates Information on maternal age, educational level, smoking status, maternal height and pre-pregnancy weight, parity and previous history of preterm delivery were collected by using face to face questionnaire. In addition, diagnosis of gestational diabetes mellitus (GDM), infant’s gestational age, birth weight and sex, were abstracted from medical records. Gestational age was evaluated based on the ultrasound examination in the first or second trimester. Pre-pregnancy body mass index (BMI; kg/m2) was calculated as the ratio of pre-pregnancy weight (kg) to squared height (m). Since the prevalence of previous history of preterm delivery and smoking exposure were quite low (1% in the control group), the authors did not include these variables for further analysis. Statistical analysis The differences between the case and control groups were evaluated by using the chi-squared test or Fisher’s exact BTZ044 test (for categorical variables) and Student’s t-test (for continuous variables). The Hardy-Weinberg equilibrium for PLA2G4C rs1366442 and PLA2G4D rs4924618 was examined.