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Published on: January 7, 2016

The shortness of Pygmies is associated with severe under-expression of the growth hormone receptor

Mauro Bozzola1, Paola Travaglino, Nicola Marziliano

  • 1Pediatric Department, University of Pavia, Pavia, Italy.

Molecular Genetics and Metabolism
|June 23, 2009
PubMed

Insights

African Pygmies exhibit idiopathic short stature (ISS) due to significantly reduced growth hormone receptor (GHR) gene expression. This finding in Pygmies may help understand ISS mechanisms in other populations.

Area of Science:

  • Endocrinology and Genetics
  • Human Growth and Development

Background:

  • Idiopathic short stature (ISS) is a complex trait influenced by genetics and environment.
  • African Pygmies are a model for non-disease-related ISS, sharing endocrine profiles with Caucasian ISS individuals.
  • Adult Pygmies have normal growth hormone (GH) but low GH-binding protein (GHBP) and insulin-like growth factor-I (IGF-I), suggesting impaired GH response.

Purpose of the Study:

  • To investigate gene expression profiles of GH and GH receptor (GHR) in African Pygmies.
  • To determine if reduced gene expression contributes to idiopathic short stature (ISS) in Pygmies.
  • To explore potential mechanisms of ISS by comparing Pygmies with normal-stature Bantu populations.

Main Methods:

  • Quantitative gene expression analysis of GH and GHR genes.
  • Comparison of gene expression levels between adult Pygmies and adult Bantu individuals.
  • Sequencing of the GHR gene to rule out sequence variants as the cause of reduced expression.

Main Results:

  • GH gene expression was 1.8-fold reduced in adult Pygmies compared to Bantu.
  • GHR gene expression was markedly reduced (8-fold) in adult Pygmies versus Bantu.
  • Reduced GHR expression correlated with lower serum IGF-I and GHBP levels and was not due to GHR gene sequence variants.

Conclusions:

  • Markedly reduced GHR gene expression is a key feature of adult African Pygmies with idiopathic short stature (ISS).
  • This downregulation of GHR expression, not sequence variants, likely underlies the impaired GH action and short stature.
  • Findings offer insights into the molecular mechanisms of ISS, potentially applicable to Caucasoid populations.

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