Session: FP20-Growth: Clinical Trials & Observational Studies
Room 122 (Moscone Center)
Poster Board SUN-627
Fifty-eight people with Ach were studied, 42 children under 18 years (20 girls, 22 boys) and 16 adults (10 women, 6 men). Plasma samples were assayed for CNP and NTproCNP by radioimmunoassay and standard deviation (SD) scores were calculated using published reference ranges (1,2). For the children, CNP SD scores were elevated at 0.78±0.85 (mean±SD), compared to age- and sex-matched controls (0±1, P<0.00001). NTproCNP SD scores (a measure of CNP biosynthesis) were elevated at 1.15±1.00. The ratio of CNP-to-NTproCNP SD score (a measure of CNP clearance) was -0.16±0.89 and was not different from the reference population. For the adults, CNP SD scores were 1.39±1.28 (P<0.001) and NTproCNP SD scores were 0.44±0.64 (P<0.05).
In healthy children, plasma NTproCNP is strongly correlated with height velocity (1). Height velocity data were available on 36 of the children with Ach (16 girls, 20 boys). For each subject, a height velocity-matched control was selected from a database of 139 healthy children without Ach. Height velocities were well matched at 4.3 cm/y (3.8–5.5 cm/y)[median (25%ile – 75%ile)] vs. 4.1 cm/y (3.8–5.5 cm/y) for controls. However, the ages of the children with Ach were considerably lower, 4.7 y (2.9–6.9 y) vs. 10.5 y (8.0–12.8 y)(P<0.0005 by Wilcoxon Signed-Rank test). CNP levels were higher in the children with Ach, 2.1 pmol/L (1.8–2.3 pmol/L) vs. 1.4 (1.3–1.8 pmol/L) in controls, as was NTproCNP, 54.5 pmol/L (46.0–61.5 pmol/L) vs. 34.6 (31.5–36.4 pmol/L)(P<0.0005 for both). For children growing at the same height velocity, CNP and NTproCNP levels were significantly higher in children with Ach.
Plasma CNP and NTproCNP concentrations are raised in Ach, demonstrating CNP resistance in vivo at the intracellular level. Whether CNP resistance contributes to the Ach phenotype, and the extent to which resistance can be overcome by exogenous CNP therapy, remain to be determined.
Nothing to Disclose: RCO, WM, TCP, AD, CD, EAE, MB
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