The exon 3-deleted growth hormone receptor: molecular and functional characterization and impact on GH/IGF-I axis in physiological and pathological conditions.

The GH receptor (GHR) plays a key role in the the function of the GH/IGF-I axis and is the major effector of human growth. A common polymorphic variant consisting of genomic exon 3 deletion or retention (d3-GHR and full-length GHR, respectively), described in 2000, has been linked with increased receptor activity due to enhanced signal transduction. Subsequent pharmacogenetic studies have addressed a possible role of GHR polymorphism on the response to recombinant human GH treatment first in short children and then in adults, many of them suggesting that growth response to GH may be influenced, at least in some aspects, by this polymorphism. Similar studies, performed in patients with acromegaly, assumed an influence of the d3- GHR variant in the relationship between GH and IGF-I levels. More recently, some studies have investigated the relation between GHR genotype and treatment with the GHR antagonist pegvisomant, suggesting a better clinical response to therapy related to d3-GHR genotype. This review provides a summary of the main pharmacogenetic studies performed on this current and still open topic.