Mutations in natriuretic peptide receptor 2 (Npr2) gene cause a rare form of short-limbed dwarfism, but its physiological effects have not been well studied.
While NPR2 mutations have been described in patients with skeletal dysplasias and idiopathic short stature (ISS), and several Npr2 and Nppc skeletal dysplasia mouse models exist, no mutations in NPPC have been described in patients to date.MethodsNPPC was screened in 668 patients (357 with disproportionate short stature and 311 with autosomal dominant ISS) and 29 additional ISS families in an ongoing whole-exome sequencing study.ResultsTwo heterozygous NPPC mutations, located in the highly conserved CNP ring, were identified.
Homozygous and/or heterozygous loss of function mutations in the natriuretic peptide receptor B (NPR2) have been reported in causing acromesomelic dysplasia, type Maroteaux with variable clinical features and idiopathic short stature with nonspecific skeletal deformities.
Activating mutations in fibroblast growth factor (FGF) receptor 3 and inactivating mutations in the NPR2 guanylyl cyclase both cause severe short stature, but how these two signaling systems interact to regulate bone growth is poorly understood.
This case reveals a novel heterozygous loss-of-function NPR2 mutation responsible for familial short stature and the good response of rhGH therapy in this patient.
Activating mutations in fibroblast growth factor receptor 3 (FGFR3) and inactivating mutations of guanylyl cyclase-B (GC-B, also called NPRB or NPR2) cause dwarfism.
C-type natriuretic peptide activation of guanylyl cyclase B (GC-B), also known as natriuretic peptide receptor B or NPR2, stimulates long bone growth, and missense mutations in GC-B cause dwarfism.
Disorders of signalling of various paracrine factors (FGFs, BMPs, WNTs, PTHrP/IHH, and CNP/NPR2) or genetic defects affecting cartilage extracellular matrix usually cause disproportionate short stature.
Mutations in the gene NPR2 have been shown to cause acromesomelic dysplasia-type Maroteaux (AMDM), an autosomal recessive skeletal disproportionate dwarfism disorder in humans.
Assuming one in 700 people unknowingly carry an NPR2 mutation, our data suggest that approximately one in 30 individuals with idiopathic short stature are carriers of NPR2 mutations.