Polymorphisms of Angiotensin Converting Enzyme and Nitric Oxide Synthase 3 Genes as Risk Factors of High-Altitude Pulmonary Edema: A Case-Control Study and Meta-Analysis

High-altitude pulmonary edema (HAPE) is a non-cardiogenic type of pulmonary edema developing altitudes >2,500 m. Angiotensin converting enzyme (ACE) and nitric oxide synthase 3 (NOS3) play important roles in regulating pulmonary vascular tone. To assess associations between genetic variants in the ACE and NOS3 genes and HAPE risk, 27 HAPE patients and 108 matched controls were genotyped and analyzed. The indicated HAPE association of the NOS3 G894T (Glu298Asp) single nucleotide polymorphism (SNP), which may change NO production, was further evaluated by a meta-analysis of six studies involving 399 HAPE patients and 495 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined with fixed-effects models. Stratification analyses of ethnicity and geographic location were performed. Significant associations were observed for the dominant model in two ACE tag SNPs influencing serum ACE concentrations (rs8066114 polymorphism: GG+CG vs. CC; rs4461142 polymorphism: TT+CT vs. CC). Furthermore, Single-locus analysis indicated significantly different distributions of G allele frequency between the cases (29.63%) and controls (17.13%) for the ACE rs8066114 polymorphism. The case-control distributions of genotype frequencies and T allele frequency of NOS3 G894T (Glu298Asp) polymorphism were significantly higher in the cases than controls, and the NOS3 G894T (Glu298Asp) SNP showed elevated HAPE risk under the dominant model (TT+GT vs. GG). Meta-analysis showed overall association of NOS3 G894T SNP with HAPE risk under the allele contrast and dominant genetic models, which remained significant for Asians. In conclusion, ACE rs8066114 and rs4461142 and NOS3 rs1799983 (G894T) polymorphisms may be associated with increased HAPE risk in Asians.