[Epigenetic inheritance of the sperm: an unexpected role of RNA]

Familial clustering of a disease in the absence of a definite Mendelian determination is not an uncommon observation. Complex multigenic systems, variable penetrance, environmental factors, as well as other ad hoc explanations are commonly invoked. On the other hand, experimental models recently generated in the mouse lead to the alternative, non-exclusive concept of the transgenerational maintenance of a pathogenic epigenetic variation. Thus, we recently identified a new mode of epigenetic inheritance mediated by RNA and micro-RNA which is released by sperm. This discovery, namely that RNA molecules present in the spermatozoon head may be possible vectors for the hereditary transfer of epigenetic modifications, may have both fundamental and medical interests.