Context: Consensus is lacking as to whether the exon 3-deleted (d3)/full-length (fl) GH receptor (GHR) polymorphism is associated with responsiveness to GH therapy.
Objective: Our objective was to evaluate, in short, prepubertal, appropriate-for-gestational age (AGA) patients, 2-yr growth response to GH therapy (31.7+/-3.5 microg/kg.d) according to exon 3-deleted/full-length GHR genotypes.
Design: We conducted a retrospective study.
Patients: We studied 106 short AGA children, 58 boys and 48 girls, 7.8+/-2.3 yr, (d3/d3 n=18, d3/fl n=42, and fl/fl n=46). The GH response to two provocative stimuli were under 10 ng/ml in 65 and one or both over 10 ng/ml in 41 patients.
Main outcome measures: Patients were followed by a single clinical team and remained prepubertal during the study. The exon 3-deleted/full-length GHR genotypes were determined and analyzed in the same hospital.
Results: Growth velocity significantly (P<0.0001) increased during the first and second years of therapy, as did height sd score (SDS). These increases were similar in each exon 3-deleted/full-length GHR genotype. Total 2-yr height gain (SDS) did not differ statistically among genotypes: 15.5+/-2.2 cm and 1.2+/-0.5 SDS in d3/d3, 15.9+/-2.0 cm and 1.3+/-0.4 SDS in d3/fl, and 15.4+/-2.1 cm and 1.1+/-0.3 SDS in fl/fl. No significant differences among the three genotypes were found in both sexes or in patients with different GH peak response to provocative stimuli for these parameters. An analysis of previously published studies was also performed.
Conclusions: These results confirm in AGA patients those previously found by us and others in small-for-gestational-age patients and suggest that neither sex nor GH peaks after provocative stimuli might influence significantly the responsiveness to GH therapy according to the exon 3-deleted/full-length GHR genotypes.