Reacción a "Reaction: new technique allows sperm to be selected for sex selection"

The aim, approach and design of the article is adequate, although its practical usefulness is limited for several reasons. Firstly, its effectiveness is limited (only 80 %) and other procedures with similar effectiveness already exist. On the other hand, it is based on the same principles that have been considered up to now, such as the difference in density between the spermatozoa containing the "X" chromosome and those containing the "Y" chromosome, so it does not provide any differential point in this aspect compared to what already exists. Finally, with regard to the technique used and its reproducibility, it cannot be assessed as it does not indicate the specific technique used. In short, in my opinion, it does not provide added value over and above the social impact that news such as this can have.  

I do not agree [as the authors say] that it is more ethically acceptable to make a sex selection through the study of the spermatozoon instead of a diagnosis on the embryo, as I consider that the ethical conditioning factor comes from the concept itself of "à la carte selection", rather than from the technique used. Even from the point of view of its effectiveness, it would currently be more ethical to make the diagnosis on the embryo than on the spermatozoon because of its greater reliability. 

We must bear in mind that the Assisted Reproduction Law (Law 14/2006) in Spain considers sex selection without indication as a very serious infraction, with a sanction that can range from 10,001 euros to one million. And it is precisely in this concept of "indication" where the limitation lies. A woman's or couple's wish to have a child of one sex or the other cannot be considered a medical indication. Law 14/2006 on Assisted Reproduction clearly indicated that assisted reproduction should have a clinical indication, and therefore allowed it to be carried out to avoid the transmission of serious hereditary diseases linked to sex, such as haemophilia, muscular dystrophy such as Duchenne or Fragile X syndrome. The rationale was that males had a high probability of manifesting the disease (50%), while females would always be healthy.  

It should be noted that at that time we did not know the mutation that caused the disease, so we could not use other more direct procedures, even though we knew that with this sex selection we were also ruling out 50% of males who would have been healthy. This is no longer done in these cases, as we are able to detect the mutation without the need for sex selection. In my opinion, whether or not to allow the application of this type of selection without medical indication should be based on a thorough analysis of the society itself, analysing whether at that moment there could be a population shift towards one or the other sex, as happened in China at the time. An intermediate solution could be to allow the selection of a second child as long as it is of a different sex than the first.   

In my opinion, this work does not improve the effectiveness of existing techniques, nor does it provide any novelty in the "basic" procedure, although it cannot be evaluated in detail, since it does not describe the procedure used. We can only highlight the social impact that news such as this can have but which, in Spain, have little chance given the current legislation.