The Role of Growth Hormone Receptor Isoforms and Their Effects in Bone Metabolism and Skeletal Fragility

Acromegaly and Growth Hormone Deficiency (GHD) are associated with skeletal fragility and with an increased prevalence of Vertebral Fractures (VFs). In the most recent years, several authors tried to investigate surrogate markers that may predict the risk of bone fragility in these endocrine disorders. The aim of this review is to evaluate the role of GH receptor polymorphisms in skeletal fragility in patients affected by GHD and acromegaly. In fact, until now, two different isoforms of the GH Receptor (GHR) were described, that differ for the presence or the absence of transcription of the exon 3 of the GHR gene. Both the isoforms produce a functioning receptor, but the exon 3-deleted isoforms (d3-GHR) has a higher sensitivity to endogenous and recombinant GH as compared to the full-length isoform (fl-GHR).