GH responsiveness in a large multinational cohort of SGA children with short stature (NESTEGG) is related to the exon 3 GHR polymorphism

Abstract

Objective: The polymorphic deletion of exon 3 of the GH receptor (d3-GHR) has recently been linked to the magnitude of growth response to recombinant human GH (rhGH) therapy in short children with or without GH deficiency. We investigated this association in a large multinational cohort from the Network of European Studies of Genes in Growth (NESTEGG), comprising short children born small for gestational age (SGA).

Design: The study included short prepubertal SGA children treated with rhGH for 1 or 2 years.

Population: Two hundred and forty white Caucasian SGA children (138 male, 102 female) aged 6.6 +/- 2.3 years with a height at -3.0 +/- 0.7 SDS at start of rhGH treatment; 193 ethnically matched controls.

Methods: The GHR polymorphism (fl/fl, fl/d3 or d3/d3) was genotyped by polymerase chain reaction (PCR) multiplex assay. Growth velocity (G/V) in cm/year and changes in GV during the first and second year of rhGH treatment were evaluated.

Results: The change in GV was significantly greater in SGA children carrying one or two copies of the d3-GHR allele (P = 0.038 for the first year and P = 0.041 for the second year of GH treatment), but the change in height was not significantly different. Birthweight was significantly lower in SGA children with the d3/d3 genotype than in SGA children with the fl/fl genotype (P = 0.034) and in those with the fl/d3 genotype (P = 0.016).

Conclusion: Our data, based on a large cohort, showed that the exon 3 GHR polymorphism is associated with responsiveness to rhGH treatment in SGA children with short stature.

Fig. 1

Change in growth velocity during the first year of GH treatment in the 240 SGA children according to the dose of rhGH: high dose 0·43 ± 0·17 mg/kg/week; low dose 0·21 ± 0·04 mg/kg/week. Results are presented as boxes with the horizontal line inside the box representing the mean and the vertical line representing the interquartile range (10th–90th centiles). The extreme values are presented as circles. The d3/d3 + fl/d3 group (or D group) is in white and the fl/fl group is in grey.

Fig. 2

Studentized residuals in the three genotype groups are calculated according to the KIGS growth prediction model for SGA, incorporating rhGH dose, age and weight at start of therapy as well as gender-adjusted midparental height. Results are presented as boxes with the horizontal line inside the box representing the mean and the vertical line representing the interquartile range (10th–90th centiles). Positive studentized residuals indicate growth that exceeded the prediction, negative values growth below the prediction. The asterisk indicates a significant difference between the predicted growth velocity and the observed growth velocity (P = 0·04).