Genetic Modifiers of Patent Ductus Arteriosus in Term Infants.

OBJECTIVE: To identify single-nucleotide polymorphisms (SNPs) in specific candidate genes associated with patent ductus arteriosus in term infants. STUDY DESIGN: We conducted an initial family-based, candidate gene study to analyze genotype data from DNA samples obtained from 171 term infants and their parents enrolled in the National Birth Defects Prevention Study (NBDPS). We performed transmission disequilibrium testing (TDT) using a panel of 55 SNPs in 17 genes. Replication of SNPs with P < .1 in the NBDPS trios was performed with a case-control strategy in an independent population. RESULTS: TDT analysis of the NBDPS trios resulted in 6 SNPs reaching the predetermined cutoff (P < .1) to be included in the replication study. These 6 SNPs were genotyped in the independent case-control population. A SNP in TGFBR2 was found to be associated with term patent ductus arteriosus in both populations after we corrected for multiple comparisons. (rs934328, TDT P = 2 × 10(-4), case-control P = 6.6 × 10(-5)). CONCLUSIONS: These findings confirm the importance of the transforming growth factor-beta pathway in the closure of the term ductus arteriosus and may suggest new therapeutic targets.

Sequence variants in oxytocin pathway genes and preterm birth: a candidate gene association study.

BACKGROUND: Preterm birth (PTB) is a complex disorder associated with significant neonatal mortality and morbidity and long-term adverse health consequences. Multiple lines of evidence suggest that genetic factors play an important role in its etiology. This study was designed to identify genetic variation associated with PTB in oxytocin pathway genes whose role in parturition is well known. METHODS: To identify common genetic variants predisposing to PTB, we genotyped 16 single nucleotide polymorphisms (SNPs) in the oxytocin (OXT), oxytocin receptor (OXTR), and leucyl/cystinyl aminopeptidase (LNPEP) genes in 651 case infants from the U.S. and one or both of their parents. In addition, we examined the role of rare genetic variation in susceptibility to PTB by conducting direct sequence analysis of OXTR in 1394 cases and 1112 controls from the U.S., Argentina, Denmark, and Finland. This study was further extended to maternal triads (maternal grandparents-mother of a case infant, N=309). We also performed in vitro analysis of selected rare OXTR missense variants to evaluate their functional importance. RESULTS: Maternal genetic effect analysis of the SNP genotype data revealed four SNPs in LNPEP that show significant association with prematurity. In our case-control sequence analysis, we detected fourteen coding variants in exon 3 of OXTR, all but four of which were found in cases only. Of the fourteen variants, three were previously unreported novel rare variants. When the sequence data from the maternal triads were analyzed using the transmission disequilibrium test, two common missense SNPs (rs4686302 and rs237902) in OXTR showed suggestive association for three gestational age subgroups. In vitro functional assays showed a significant difference in ligand binding between wild-type and two mutant receptors. CONCLUSIONS: Our study suggests an association between maternal common polymorphisms in LNPEP and susceptibility to PTB. Maternal OXTR missense SNPs rs4686302 and rs237902 may have gestational age-dependent effects on prematurity. Most of the OXTR rare variants identified do not appear to significantly contribute to the risk of PTB, but those shown to affect receptor function in our in vitro study warrant further investigation. Future studies with larger sample sizes are needed to confirm the findings of this study.