Association of genetic variation with gene expression and protein abundance within the natriuretic peptide pathway.

The natriuretic peptide (NP) system is a critical physiologic pathway in heart failure with wide individual variability in functioning. We investigated the genetic component by testing the association of single nucleotide polymorphisms (SNP) with RNA and protein expression. Samples of DNA, RNA, and tissue from human kidney (n = 103) underwent genotyping, RT-PCR, and protein quantitation (in lysates), for four candidate genes [NP receptor 1 (NPR1), NPR2, and NPR3 and membrane metalloendopeptidase]. The association of genetic variation with expression was tested using linear regression for individual SNPs, and a principal components (PC) method for overall gene variation. Eleven SNPs in NPR2 were significantly associated with protein expression (false discovery rate ≤0.05), but not RNA quantity. RNA and protein quantity correlated poorly with each other. The PC analysis showed only NPR2 as significant. Assessment of the clinical impact of NPR2 genetic variation is needed.