Free and total leptin serum levels and soluble leptin receptors levels in two models of genetic obesity: the Prader-Willi and the Down syndromes

Metabolism. 2007 Aug;56(8):1076-80. doi: 10.1016/j.metabol.2007.03.016.


Alterations in energy balance and feeding behavior and the subsequent high frequency of obesity are hallmarks of 2 chromosomal diseases: the Prader-Willi syndrome (PWS) and the Down syndrome (DS). Leptin, an important regulator of food intake and energy homeostasis, circulates in 2 forms: a free, therefore active, fraction and a fraction bound to the soluble leptin receptor, whose bioavailability consequently participates in the regulation of leptin action. To investigate the possible role of the free-bound leptin balance in the pathogenesis of obesity in PWS and DS, we enrolled 7 obese women with DS, 5 obese women with PWS, 7 obese women, and 7 normal-weight healthy control women. Basal hormonal concentrations, total and free leptin levels, and leptin receptors levels were measured in plasma samples obtained from the 4 groups. No significant differences were observed in the hormonal milieu. Women with DS exhibited lower total leptin concentrations (P<.01), comparable leptin receptor level and, therefore, lower free leptin values (P<.01) when compared with obese controls, then resembling the profile peculiar to normal-weight control women. At variance, subjects with PWS did not differ from obese controls regarding both leptin and leptin receptor levels. Our data suggest that, whereas subjects with PWS have a leptin assessment corresponding to their degree of obesity, subjects with DS may have a defect in the secretion of leptin that could at least partially account for this form of syndromal obesity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Down Syndrome / blood*
  • Down Syndrome / complications
  • Down Syndrome / genetics*
  • Female
  • Hormones / blood
  • Humans
  • Leptin / blood*
  • Obesity / blood*
  • Obesity / etiology
  • Obesity / genetics*
  • Prader-Willi Syndrome / blood*
  • Prader-Willi Syndrome / complications
  • Prader-Willi Syndrome / genetics*
  • Radioimmunoassay
  • Receptors, Cell Surface / blood*
  • Receptors, Leptin


  • Hormones
  • LEPR protein, human
  • Leptin
  • Receptors, Cell Surface
  • Receptors, Leptin