HNF1A and Patent ductus arteriosus: Interestingly, genome-wide association (GWA) studies have recently identified certain single nucleotide polymorphisms (SNPs) in the HNF1A locus as risk factors for developing PDA (Pierce and Ahsan, 2011; Li et al., 2012; Wei et al., 2012), although the mechanism by which these SNPs exert their influence is currently unknown.