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Unformatted text preview: m), and many, many more. The people with these
karyotypes can range from apparently normal females to females with
hypoplastic (underdeveloped) ovaries to Turner syndrome females, to
females with vestigial streak ovaries, to females who look like males,
to males with dysgenic testes, to normal males.9 Like light through a
prism, as the X chromosome splinters, so do our old ideas about what
makes a man or woman.
Chimeras: When There Are Two of Me
In Greek mythology, the Chimera was a fire-breathing monster with the
head of a lion, the body of a goat, and the tail of a serpent. In literature,
a chimera is something fanciful, often imaginary. And in science, a chimera is one creature made from the cells of two or more animals. The
word itself is a chimera made from parts of many different histories. It
is also a word that drives certain people’s lives. Where Our Sexes Come From 67 Mosaics develop from a single zygote. Chimeras, on the other hand,
arise from two different zygotes.
Many mysterious things are possible during the earliest stages of
embryonic development. For example, some eggs with two nuclei survive through to ovulation, and it is sometimes possible for two different sperm to fertilize these binucleate eggs. Occasionally, instead of
splitting into two separate individuals, this sort of zygote develops into
one person with two different types of cells—46,XX and 46,XY, for
example—male and female all at once. On other occasions two separate
zygotes may fuse and develop into a single fetus, again with two completely different types of cells—one from zygote A and one from zygote
B, each with its own karyotype.
While these are the most common ways to create chimeras, they
are not the only means by which a person can come to be a collection
of two (or more) distinct types of cells, each with its own set of chromosomes.
The only difference between mosaic and chimeric people is that
in mosaics the two cell types originate from a single cell and a single
nucleus. In chimeras the two types of cells originate from separate cells
of distinct genetic origins. Because of that, chimeras usually develop
very much like their mosaic counterparts, creating a whole spectrum of
people ranging from male to female.
Just how many of us are chimeric? No one knows. Often, sex chromosome chimeras show no symptoms at all. Everything depends on
whether the chimerism extends to the gonads. If all of the cells of the
gonads have two X chromosomes, the chimera develops as a normal
female. If all of the cells of the gonads have one X and one Y chromosome, the chimera develops as a normal male, usually. However, if the
cells of the gonads are mixed, then it is possible that the chimera might
have one ovary and one testis, two ovotestes, one ovotestis and one
ovary, or one ovotestis and one testis. And the ovotestis could be mostly
ovary or mostly testis. The consequences of all this vary considerably.
But, in the end, the external and internal genitalia can range from normal female to intersex to normal male and all the points in between. 68 Between XX and XY Kailana Sidrandi Alaniz
Location: Washington, USA
On October 10, 1970, the day she was born, she was named Dorothy
Maree Alaniz—a baby girl. Curiously, though, no one filled out a birth
certificate that day. When the certificate was finally filed on November
5, the name on it was Rudolph Andrew Alaniz. Within less than one
month after her birth, this girl became a boy.
Then, when he was about eighteen months old, the doctors performed a laparoscopy on Rudy. Today, Kailana (born Dorothy/Rudy)
feels certain that the doctors discovered then that Rudy in fact had ovaries (possibly rudimentary ovaries or ovotestes—gonads with both testicular and ovarian tissue) and that he/she was a 46,XY/45,XO mosaic.
That meant that some of Rudy’s cells had the normal number of chromosomes, forty-six, including normal X and Y sex chromosomes, and
some did not.
Rudy’s mosaicism raised some serious questions about his sex—
was he a boy or a girl? His parents had always wanted a boy, and so all
memories of Dorothy evaporated. Rudolph he would remain. So even
though most Turner syndrome patients, especially those with any ovarian tissue, are raised as girls, Rudolph faced life as a boy.
According to Kailana, it seems probable that a few more early surgeries brought Rudy’s body more in line with his parents’ expectations,
and the feminine pronoun disappeared from his medical records. Finally,
everyone seemed sure of Rudy’s masculinity—except maybe Rudy, who
by age twelve was having serious doubts. His pediatrician and parents
constantly asked Rudy if he was happy as a boy, and he repeatedly told
them that he was not happy and felt like he should have been a girl.
But it wasn’t until Rudy joined the army ten years later that he
began to suspect how little he had truly been told about just who he
was. Because of a back injury, the young man was sent for an MRI. That
MRI changed his l...
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This document was uploaded on 02/04/2014.
- Spring '14