Background

Regulation of Transposable Elements (TEs) expression has already been associated with complex human diseases, in particular cancer [1]. Also, complex diseases cannot be explained only by genetic factors and are likely to be the result of gene-environment interactions with the contribution of TEs. The detection of retroviral transcripts in the brains of schizophrenics suggests that activation or upregulation of distinct human endogenous retroviruses (HERVs) may play a role in the etiopatho-genesis of neuropsychiatric diseases [2], with increasing complications if we consider that TE insertions generate somatic mosaicism in neuronal cells [3]. In addition, mobile elements have been heavily involved in tissue-specific promoter activity [4] that makes them good candidates for brain specific activation of genes related to schizophrenia. Eventually, TEs are thought to be important in regulation of methylation and DNA accessibility to transcription factors [5]. They are also an important source of small RNAs, which usually act to silence TEs [6]; a particular family of small RNAs, miRNAs, has already been shown to alter neural receptors' function [7].