Thursday, March 9, 2017


wall painting from Herculaneum
In the previous post I mentioned that in biological chimeras (individuals formed by the fusion of two independent fertilized eggs) it may happen that most of the body belongs to one sex, but the genital organs belong to the other. This phenomenon is called pseudohermaphroditism. It can also be the case (although it is rarer) that the same individual has the two genital organs, complete or incomplete. This phenomenon was formerly called hermaphroditismname of a son of Hermes and Aphrodite in Greek mythology, but these cases have recently been included in the concept of intersexa more general term that covers all cases that do not fit the usual definition of male or female bodies, reserving the word hermaphroditism for animals or plants where that condition is normal.
To clarify things, normal members of the human species have 46 chromosomes (23 pairs), with pair 23 formed by the two sex chromosomes, which are responsible for the differences between the sexes. They can be either two X chromosomes (one inherited from the mother, the other from the father); this genetic endowment is called XX and the individual is female. Or they can be an X chromosome (inherited from the mother) and a Y chromosome (inherited from the father); this genetic endowment is called XY and the individual is male. But in addition to these two cases there are others, much less frequent. Let us quote a few (frequency figures are taken from Wikipedia):

  • Klinefelter Syndrome: It is a chromosome 23 trisomy. The affected individual has 47 chromosomes rather than 46. The sexual chromosome X is supernumerary. The sexual genetic endowment is represented as XXY. Externally they look like males, although they are not usually fertile. One out of every 1000 births can be classified in this group, although some authors do not consider it intersex.
  • Turner syndrome: This is the opposite of the previous one. The affected individual has 45 chromosomes because one of the two sex chromosomes has been lost. Their sexual genetic endowment is represented by X0. Externally they are females, although they are often unfertile (except with artificial fertilization). It affects one in 2750 births, although some authors do not consider it intersex.
  • Androgen insensitivity syndrome: They are individuals with XY sexual genetic endowment, but whose cells do not respond to male hormones, so that in extreme cases they can develop with female sexual organs or underdeveloped male organs. It affects one in 13,000 births.
  • Congenital Adrenal Hyperplasia: Result of a mutation that interferes with the production in the adrenal capsules of sex hormones from cholesterol. Their effect may be a superproduction of male hormones (androgens) which leads to extreme virilization in XY males and to ambiguous genitalia in XX females. Or it can give rise to underproduction of androgens or estrogens, which may result in XY males with apparently female genitalia or females with hypogonadism. It affects one in every 1000 births, although many cases are not discovered until many years later.
  • Ovotestis: These are individuals, usually XY, who have a partially male and partially female sex organ. It happens once per 83,000 births.
  • MRKH syndrome or vaginal agenesis: It occurs in XX individuals who have functional ovaries but lack the uterus and sometimes the vagina. It occurs once every 5,000 births.
  • Gonadal dysgenesis: The result of a problem during embryonic development that gives rise to the loss of the gonads. It can affect both XY and XX, and in both cases the external appearance is female. It happens once every 150,000 births.
Karyotype of a human with
trisomy 21 (Down syndrome)
The total number of births with any of these types of intersex is of the order of 1.5% if all the doubtful cases are counted, as well as those that are not detected until puberty or even later. Other researchers, who do not accept this broad definition, reduce them to less than 0.5%.
Obviously, intersex individuals are human beings with every right. However, I can think of two pertinent questions:
  1. Is there a justification for 99% of all children to be led into confusion, in order to protect the remaining 1% from alleged discrimination? Can’t the same result be got in some other way?
  2. Why are human beings conceived with trisomy 21 (Down syndrome) denied the right to life, to the point that, in many Western countries, in practice they are not allowed to be born?

Manuel Alfonseca

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