What we need to know when a male person has two X chromosomes, and female – X and Y. The topic became much discussed after the International Olympic Committee (IOC) allowed two women's boxing competitors - Algeria's Imane Khelief and Taiwan's Lin Yu-Tin - to participate in the Paris Games, despite doubts about their biological sex . Both have elevated testosterone levels and failed the gender test last year, which has kept them out of the World Boxing Championships by the International Boxing Federation. This caused a big scandal at the Olympics in France. Including we are damaged because Yu-Tin faced our Svetlana Kamenova and defeated her. Prof. Alexey Savov - head of the National Genetic Laboratory, spoke to FAKTI on the subject.
- Prof. Savov, how rare a natural phenomenon is it for a male person to have two X chromosomes, and a female person – X and Y?
- These are possible but rare conditions. And given that they are indeed rare conditions, in numbers we have data that approximately one in 25,000 males could be born with two X chromosomes, and one in 25,000-30,000 females with both X and Y.
- Of course, the occasion to talk about chromosomes is the scandal regarding the gender identity of boxers Iman Khalif (Algeria) and Lin Yu-ting (Taipei). How do confused chromosomes affect the body and do they give an advantage in sports – endurance, strength...
- Certainly the physical indicators of individuals who have confused or at least different from the expected chromosomes may have some deviations. What do I mean. In men with two X chromosomes, testosterone levels will be significantly lower, although outwardly looking at their habit, the external sexual markings correspond absolutely to the male sex. As for women with X and Y chromosomes, things are more complicated from a medical point of view. The question is why, if a Y chromosome is present, it does not determine male sex. What is the problem? Both genes on the Y chromosome and genes on the other chromosomes are involved in shaping the male sex. For example, if there is a genetic defect that affects the androgen receptor, even if there is a Y chromosome available to regulate testosterone production, the testosterone receptor, which is controlled by another gene, will not respond to it, and already in embryonic development, sex will be formed as female. This condition is known as "Androgen Insensitivity Syndrome".
Here I draw attention to the fact that in these women the level of testosterone is expected to be high and within the limits of what is normal for men.
Another possible cause of a disorder in sexual development is that there is a defect in the very gene involved in determining male sex located on the Y chromosome. In these cases, females with X and Y chromosomes will have female-specific testosterone levels. If we assume that testosterone is a key factor on the basis of which the musculature, the bone system will develop, the way a muscle will withstand a load, then properties such as speed, strength, etc. will obviously be different. I'm not a sports medicine specialist to be able to give a specific example to what extent higher testosterone levels would benefit a female athlete regardless of the sources of that female's increased testosterone. I logically assume that there will definitely be advantages.
- Most often when this thing is discovered, when you encounter such oddities…
- We encounter only within the framework of solving medical problems in couples with infertility. The example is very simple. Both men with two X chromosomes and women with both X and Y chromosomes have a problem with reproduction. In men, the problem is expressed in the fact that the spermogram is of greatly reduced quality and most often no functional spermatozoa are detected. In searching for the answer to this medical problem, one of the steps is to do a chromosome study. In rare cases - in my 30 years of practice, I can think of two or three similar cases, we find that the man has two X chromosomes. In women, things become visible earlier. Girls with X and Y chromosomes from birth and throughout childhood develop normally with typical female behavior and characteristics.
When they reach puberty, they do not menstruate.
In these cases, endocrinological examinations, gynecological examinations and a genetic test for chromosomes are appointed. If the girl is found to have X and Y chromosomes, this gives an answer as to the cause of the reproductive problems.
- And how do you explain a failed gender test, as claimed by the International Boxing Association, that both were suspended from the World Championships in Doha last year?
- As a genetic test for gender, I explain it in the following way. Gender verification has historically gone through several steps. The first is checking the external genitalia. If we want to see if a man is a man and a woman if she is a woman, the external visible sex marks are checked. It is possible in some cases to see deviations that do not put the respective individuals into the typical male or female category. Something is missing or more special about the external genitalia. In ladies, an examination could be done to see if there is a uterus and ovaries available. Nowadays, with an ultrasound examination, this is not a problem.
- Is this something routine?
- Yes. It is possible, even without having a connection with the sex chromosomes, to have various abnormalities of the internal sex organs - uterus and ovaries. But back to gender testing - it started as early as the 1940s with a physical exam confirming gender. Later, in the late 1950s, sex chromosome testing began to be used. This approach has been far more acceptable than physical examinations, but although in rare cases the test results cannot be interpreted unambiguously.
- When can a behavioral difference be noticed in the behavior of men and women with atypical chromosomes?
- I assure you that purely behaviorally men with two X chromosomes are in no way inferior to any man with X and Y chromosomes. Just as women with an X and a Y chromosome are not inferior to any woman with two X chromosomes. Another test in athletes is related to testosterone levels. There is a significant difference in testosterone ranges between men and women, with men at least about 8 times higher. Abnormally high levels of testosterone in a woman can be seen for other reasons, not related to sex chromosomes. For example, the presence of polycystic ovaries or congenital adrenal hyperplasia.
In reality, none of the possible and applied tests is absolutely unequivocal.
In this line of thought, the rules adopted by a sports organization - which tests will be considered valid to determine and accordingly categorize individuals in relation to gender, should be very clearly spelled out and rest on categorical arguments. As such, it should be based on relevant studies regarding the reliability of any of the tests. It is obvious that there is no universal test. Now what happens at the Olympics is a curious case, but I wouldn't call it scandalous. I have no guesses because there is no information about what test they were subjected to, what the data from those tests are, etc.
- A woman with X and Y chromosomes cannot have children or can hardly have children?
- Such women without assisted reproduction could not have children because their ovaries do not function properly and there are no eggs. Not infrequently the uterus is underdeveloped. I'll spare you the details, but in such girls, hormone therapy is recommended at puberty to develop secondary birthmarks. Some of the women even get menstruation. There are also reported cases of pregnancy achieved with donor material.
I want to share another rare and interesting case of deviations in sexual development. The team of the National Genetic Laboratory has its own studies in this direction. This condition is called “5 alpha reductase deficiency“ and affects testosterone metabolism. Boys who have this genetic defect are born with quite similar, even almost identical, female external genitalia, which may go unnoticed in infancy and childhood. Genetically, they have normal male sex chromosomes, internal genital markings are typically male, but after birth the testes remain in the abdominal cavity. I wonder how these boys will be registered - most likely as girls. And it is important to pay attention to their behavioral development during childhood. Will they socialize like girls, or will they show different interests characteristic of boys.
When puberty is reached, other mechanisms are activated in the body and "virilization" begins with them. i.e. development of male characteristics.
Male external sexual characteristics are formed - height, voice, genitals, etc. I then think about what support these people need to understand and accept what is happening to them. The cases reviewed show how complex and diverse mechanisms are involved in gender determination. For this we are talking about biological, genetic, social sex. I hope that when such topics are discussed, society will accept that all these conditions are explainable deviations in human biology and treat them with understanding.