Alu elements and human common diseases like obesity.

In the past few years the epigenetic impact on human diseases has been studied extensively. However, a controversial debate remains about the influence of environmental factors on the genetic determination of DNA methylation patterns. Although DNA methylation defects have been described in imprinting diseases and linked to cancer development, its impact on common diseases like obesity has yet to be elucidated. In our study we observed a hypermethylation variant of the POMC gene in obese children, which plays a key role in body weight regulation. Phylogenetic analyses reveal a close relationship between the POMC DNA methylation at this site and the presence of primate specific Alu elements. In this commentary we will extensively discuss our observations, including comments on the current debate about the impact of transposable elements on DNA methylation and on the development of human disease in general.