The growth hormone receptor (GHR) polymorphism in growth-retarded children with Cushing disease: lack of association with growth and measures of the somatotropic axis

Abstract

Pediatric Cushing disease (CD) often presents with short stature, but we have observed significant inter-individual variability in the growth delay caused by endogenous hypercortisolism. Glucocorticoids cause growth retardation by affecting the growth hormone (GH) - insulin-like growth factor-1 (IGF 1) somatotropic axis, but also other, GH-independent sites. Recently, the GH receptor (GHR) gene was found to have a common polymorphism (P) that leads to a deletion (d3) or retention of exon 3. In this study, we tested the hypothesis that the GH receptor polymorphism (GHR-P) maybe one of the significant variants that determines the degree of growth delay among patients with CD. GHR genotyping was performed on 56 children with newly diagnosed CD (24 females, 32 males, mean age of 12.9+/-3.3 years) who were followed at our institution between the years 1997-2007. Correlation analysis included genotype, measures of growth and the somatotropic axis, and anthropometrics. Within the group, 31 (12 girls, 19 boys) expressed the full length GHR allele, 10 (4 girls, 6 boys) were d3-GHR homozygotes and 15 (7 girls, 8 boys) were d3-GHR heterozygotes. No significant differences were found between the GHR genotypes and patient's height and/or growth velocity, or any other measures that we evaluated. The presence of a well-studied and common GHR polymorphism does not appear to be responsible for the variability of growth delay observed in patients with Cushing disease.

Figure 1

Height and BMI Z scores and IGF-1 levels SDS in patients with CD according to GHR genotypes; each point represents a single patient. Horizontal lines indicate mean values.