C-type natriuretic peptide and overgrowth.

Natriuretic peptides are a family of structurally related peptides with different distinct biological effects. C-type natriuretic peptide (CNP)-mediated signaling is important for endochondral ossification and intervenes in the control of chondrocyte maturation by regulating the balance between proliferation and terminal differentiation. CNP is encoded by the NPPC gene on human chromosome 2 for which, so far, no mutations have been described in humans. Recently, two independent articles reported the description of 3 patients with a similar clinical phenotype characterized by the presence of skeletal anomalies and overgrowth. In all 3 cases, the clinical picture was associated with the presence of a balanced translocation involving chromosome 2 and causing overexpression of the NPPC gene and an increased plasma concentration of its product, CNP. Transcriptional dysregulation of NPPC has been ascribed to the separation of the gene unit from the long-range regulatory element with a transcriptional silencing effect on its expression and CNP overproduction has been correlated to the skeletal overgrowth phenotype observed.