Bi-allelic Loss-of-Function Mutations in the NPR-C Receptor Result in Enhanced Growth and Connective Tissue Abnormalities.

The natriuretic peptide signaling pathway has been implicated in many cellular processes, including endochondral ossification and bone growth. More precisely, different mutations in the NPR-B receptor and the CNP ligand have been identified in individuals with either short or tall stature. In this study we show that the NPR-C receptor (encoded by NPR3) is also important for the regulation of linear bone growth. We report four individuals, originating from three different families, with a phenotype characterized by tall stature, long digits, and extra epiphyses in the hands and feet. In addition, aortic dilatation was observed in two of these families. In each affected individual, we identified a bi-allelic loss-of-function mutation in NPR3. The missense mutations (c.442T>C [p.Ser148Pro] and c.1088A>T [p.Asp363Val]) resulted in intracellular retention of the NPR-C receptor and absent localization on the plasma membrane, whereas the nonsense mutation (c.1524delC [p.Tyr508∗]) resulted in nonsense-mediated mRNA decay. Biochemical analysis of plasma from two affected and unrelated individuals revealed a reduced NTproNP/NP ratio for all ligands and also high cGMP levels. These data strongly suggest a reduced clearance of natriuretic peptides by the defective NPR-C receptor and consequently increased activity of the NPR-A/B receptors. In conclusion, this study demonstrates that loss-of-function mutations in NPR3 result in increased NPR-A/B signaling activity and cause a phenotype marked by enhanced bone growth and cardiovascular abnormalities.

Amino-terminal pro-C-type natriuretic peptide in heart failure.

The levels and pathophysiological role of amino terminal C-type natriuretic peptide in heart failure are unknown. The potential of plasma amino-terminal C-type natriuretic peptide (N-CNP) as a marker of cardiac function was investigated in symptomatic patients. In 305 patients with recent-onset dyspnea and/or peripheral edema, presenting to primary care, assay of plasma amino-terminal C-type natriuretic peptide and other plasma vasoactive hormones was conducted together with echocardiography. Heart failure was diagnosed in 77 (of the 305) patients by rigorous application of predefined criteria. Plasma amino-terminal C-type natriuretic peptide concentrations were elevated in patients with heart failure, and by univariate analysis were related to age, renal function, and other hormones. On multivariate analysis, tertile of plasma N-CNP interacted with tertile of plasma amino-terminal B-type natriuretic peptide to predict heart failure independent of age, gender, renal function, or echocardiographic left ventricular fractional shortening. N-CNP showed significant relations to concurrent plasma CNP, atrial natriuretic peptide (ANP), N-ANP, B-type (or brain) natriuretic peptide (BNP), N-BNP, endothelin-1, and adrenomedullin but not to echocardiographic indicators of left ventricular systolic function. Plasma amino-terminal C-type natriuretic peptide is elevated in heart failure and is related to other plasma hormones in heart failure. These findings suggest a possible compensatory response from the peripheral vasculature to heart failure by an endothelium-based vasodilator peptide and mandate further exploration of the role of C-type natriuretic peptide in this condition.