This letter should not have been necessary. There are two, and only two, sexes. That should be the starting point for all discussions of transgender issues. Here’s an excerpt from an Irish Journal of Medical Science letter titled: “The Reality of Sex“:

We regard the claim that sex is neither fixed nor binary to be entirely without scientific merit—there are two sexes, male and female, and in humans, sex is immutable (disorders of sexual development are very rare and, in any event, do not result in any additional sexes). Such politically motivated policies and statements have no place in scientific journals. It is essential that impartiality be maintained in order to preserve public trust in science as a process dedicated to producing shared knowledge.

We call upon authors and editors to resist non-scientific pressures to suppress honest and accurate discussion of these matters, particularly in the field of medicine where diagnosis, prognosis and treatment can depend on a patient’s sex.