Background: The majority of children who present for evaluation of tall stature fall under the diagnosis of constitutional tall stature (CTS).
Methods: To investigate mechanisms of tall stature, we evaluated serum IGF-I values and the expression of the GHR gene in the peripheral blood cells of 46 subjects with normal height, 38 with tall stature and 30 healthy children with short stature.
Results: Our results showed significantly lower IGF-I levels in children with short stature (-0.57±0.18 SDS) compared to control children (0.056±0.19 SDS; p<0.0001) and to subjects with tall stature (0.594±0.17; p=0.00067). Furthermore, we found significantly higher GHR gene expression levels in tall children (321.84±90.04 agGHR/5×105agGAPDH) compared with other groups of subjects (short children: 30.13±7.5 agGHR/5×105agGAPDH, p<0.0001; controls: 86.81ag±19.5 GHR/5×105agGAPDH, p=0.035). The GHR gene expression level in short children was significantly lower compared with control subjects (p=0.0068).
Conclusions: Significantly higher GHR gene expression levels in tall subjects suggests a sensitization of the GHR-IGF system leading to overgrowth in CTS.
Keywords: GHR gene; IGF-I; growth; growth hormone (GH); growth hormone-binding protein (GHBP); tall children.