Functional study of polymorphisms in the promoter region of the endothelin-1 gene in Pulmonary Arterial Hypertension

Introduction: The aim of the study was to look for potentially pathogenic mutations in the promoter region, the UTR region and the body of the endothelin 1 gene (EDN-1) in patients with PAH. In this work we describe the findings in the promoter región Methods: Patients diagnosed with PAH group I were included. DNA was extracted from peripheral lymphocytes. The sequencing was performed by the Sanger method. A luciferase assay was used for the functional study. In the study of potentially pathogenic polymorphisms, the frequency estimated in the general population was compared with the frequency found in patients. Results: A recurrent single nucleotide polymorphism (SNP) was found in patients with both idiopathic PAH and in those associated with connective tissue diseases in the promoter region of the gene (rs397751713) consisting of an adenine deletion. By means of luciferase analysis of the complete promoter región of the gene, it was found that this genotype has an important regulatory effect. The genotypes - / -, - / A and A / A were tested; obtaining a 30% higher expression in homozygotes for A / A, significantly more frequent in patients than in controls (p <0.0001). The heterozygotes had expression levels equal to homozygotes - / -. The wild-type adenine genotype causes two transcription factors (PPARgamma and KLF4) to lose their binding site. Both transcription factors (especially KLF4) have been linked to the development of PAH Conclusions: Some patients with idiopathic and associated PAH are carriers of a polymorphism in the EDN-1 gene that functionally supposes an increase in ET-1 activity and could have importance in the development of the disease