Weismann Barrier

The Weismann barrier is the principle, proposed by August Weismann, that hereditary information moves only from genes to body cells, and never in reverse. In more precise terminology hereditary information moves only from germline cells to somatic cells (that is, soma to germline feedback is impossible). This does not refer to the central dogma of molecular biology which states that no sequential information can travel from protein to DNA or RNA.

The Weismann barrier is very important as it has implications for human gene therapy. If the Weismann barrier is permeable, then genetic treatments of somatic cells may actually result in a heritable change to the genome, possibly resulting in the genetic engineering of the human species rather than just individuals. It also has implications in our understanding of evolution as it would imply that species aren't nearly as separable genetically as we once thought. Furthermore it would open the door to the existence of certain Lamarckian concepts that previously had no supporting mechanism.

The use of this theory is sometimes referred to as Weismannism.