The Obstructive Sleep Apnea (OSA) disorder may lead to serious complications. The development of OSA is influenced in general by combination of both genetic and environmental factors. In particular, Single Nucleotide Polymorphisms (SNPs) were suggested to contribute to the development of OSA and its severity. The current project focused on the SNP on rs198389 site of the Brain natriuretic peptide (BNP) gene, hypothesizing its association with OSA. BNP produces both BNP hormone and N-terminal prohormone of brain natriuretic peptide (NT-proBNP). It has been previously found that SNP on the rs198389 site of the BNP gene affects the cardiovascular health and blood circulating levels of BNP and NT-proBNP.This project is the novel study to investigate the associations of rs198389 SNP of the BNP gene in the Swedish Randomized Intervention with Constant positive airway pressure treatment in Coronary Artery Disorder and Sleep Apnea (RICCADSA) cohort. The cohort represents patients with both Sleep Apnea (SA) and Coronary Artery Disorder (CAD). Genotypes for rs198389 SNP were identified for 157 DNA samples from RICCADSA cohort by using the PCR and Restriction Fragment Length Polymorphism (RFLP) analysis. Statistical analysis was performed to find the associations between rs198389 genotypes and OSA severity, its comorbidities, as well as circulating levels of NT-proBNP.An association between BNP rs198389 polymorphism and the proportion of Acute Myocardial Infarction (AMI) baseline cases was detected for OSA patients. No other statistically significant associations were found. Further studies are suggested with larger cohort, including healthy control population, to validate the produced results.