Reply to "Response to: Dittrich et al.: Non-Embryo-Destructive Extraction of Pluripotent Embryonic Stem Cells - Overlooked Legal Prohibitions, Professional Legal Consequences and Inconsistencies in Patent Law".

In the spirit of productive scientific discussion we would like to start by thanking Faltus and Storz [1] for their comments. We have studied them carefully and would like to add the following comments from our perspective: 1. Faltus and Storz were correct in stating that the German Embryo Protection Act (Embryonenschutzgesetz, ESchG) and the expansion of some of its points in the German Preimplantation Diagnosis Act (Präimplantationsgesetz, PräImpG) do not specify whether biopsies can be taken of cells from the inner cell mass (ICM) or whether biopsies should be trophectoderm biopsies (TEB). But the choice of biopsy must depend on which procedure is medically advisable and reasonable. All other considerations must be subordinate. In particular, legal considerations cannot define the choice of medical technique. Biopsies of the inner cell mass (ICM) could soon become an important topic, as increasing numbers of publications are raising doubts about whether the chromosomal findings following the trophectoderm biopsies always mirror the genetics of the ICM, i.e., whether they might be offering false-negative results. Should these doubts be confirmed on a large scale, then biopsies of the ICM would indeed represent the “approach of choice”, as otherwise embryos with an intact genetic configuration will be discarded because the findings of the TEB came to a different conclusion. 2. Based on numerous publications on carrying out preimplantation genetic diagnosis (PIGD) on Day 3, an approach that is widely used outside Germany, we know that the extraction of 2 of 8 blastomeres can be done without complications and does not represent a “risk to the existence” of the embryo.