Objectives: The mutations of growth hormone receptor (GHR) gene results in growth hormone insensitivity (Laron syndrome) or partial growth hormone insensitivity. This study aimed to understand the relation between mutations of GHR gene and short stature with non-growth-hormone deficiency, and the clinical feature of the patients with the GHR gene mutations.
Methods: (1) Forty-seven patients with non-growth-hormone deficiency and short stature were enrolled in this study, 33 were male and 14 female. The age of the patients were at a range of 2 - 16 years. (2) The mutations of GHR gene were identified by PCR-SSCP and DNA sequencing. (3) The characteristics of the GHR mutation was assumed by screening for the same mutations in patients' family members and the control samples.
Results: (1) Four GHR mutations were identified in 5 patients with non-growth-hormone deficiency: H56R, G148E, IVS6-30, -31CA > TG and IVS8 + 10G > C. These mutations were located within the extracellular domain of GHR and not reported before. Five patients were the heterozygous of H56R, G148E, IVS6-30, -31CA > TG and IVS8 + 10G > C. The detection rate of mutant heterozygous individual accounted for 10.6% (5/47). The mutations were considered non-polymorphism by the GHR gene analysis in patients' family members and control samples. (2) Comparison of the amino acid sequence of different species and the position of the mutations H56R and G148E in the GHR protein structure suggested impact of the mutations on the protein function. (3) A polymorphism site was identified in exon 6 of GHR gene: G168G (GGA > GGG). The allelic frequency of G168G had no difference between the patients with non-growth-hormone deficiency and control samples but had significant difference between Chinese and Caucasian. It seems that the G168G was a polymorphism and has no relationship with the height stature. However, there was the allele diversity in different races.
Conclusion: The mutations of GHR gene were detected in the patients with non-growth-hormone deficiency. Special attention should be paid clinically to its potential pathogenesis for short stature.