ESPE Abstracts

Introduction: Skeletal dysplasia is a heterogeneous group of disease, leading to abnormal enchondral ossification and typing of the disease is quite complex. C-type natriuretic peptide (CNP), one of the members of the natriuretic peptide family, has been implicated to play a role in bone development. CNP levels were high in some types of the skeletal dysplasia.

Objective: The aim of this study is to evaluate the possibility of using CNP, as a marker for skeletal dysplasia types and to investigate its role in typing.

Methods: Thirty-seven patients [ages 6 months to 18 years (26 girls, 11 boys)], who accepted to participate in the study from 75 skeletal dysplasia patients were included. All subjects were physically examined and anthropometric measurements were obtained, bone surveys were evaluated. 49 healthy children [ages 6 months to 18 years (24 girls, 25 boys)], were included as a control group. ELISA method was used to assess CNP (pg/ml) plasma levels. The patient group consisted of 17 patients (45.9%) with achondroplasia, 6 patients (16.2%) with spondyloepiphysial dysplasia, 5 patients (13.5%) with metaphysical dysplasia, 2 patients (5.4%) with epiphysial dysplasia, 2 patients (5.4%) with hypochondroplasia, one patient with acromesomelic dysplasia (2.7%) and 4 patients (10.8%) with unclassified skeletal dysplasia. Genetic mutation analyses were performed on 16 of the patients previously and 16 heterozygous mutations were found [9 (53.6%) of these were p.G379R, 3 (17.6%) were p.G308R, 1 (2.7%) was p.N540K and 1 (2.7%) was p.N542K].

Results: The height SD scores (SDS) of the patient group were −4.58±2.87 (n=37) and the height SD scores (SDS) of the control group were 0.05±0.79 (n=49) (P<0.001). No significant difference was found between median CNP concentration of the patient group and the control group (P=0.207). On the other hand, median CNP of the achondroplasia patients (n=17) were higher than the control group (n=49) (P=0.032). CNP concentration of the patient group was 1.31±1.40 ng/ml (n=37) and CNP concentration of the control group was 1.04±1.40 ng/ml (n=49) (P=0.207), whereas CNP concentration of achondroplasia patients [1.79±1.64 ng/ml (n=17)] was higher than the control group] (P 0.032). CNP values were similar in both males and females. (male=51; female=35).

Conclusion: Achondroplasia patients have elevated plasma levels of CNP. In order to use CNP as a marker for the diagnosis and typing of skeletal dysplasia, more clinical studies with molecular genetic analyzes are needed.