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Thread: Girl with Y chromosome sheds light on maleness

  1. #1

    Girl with Y chromosome sheds light on maleness

    Source:
    Girl with Y chromosome sheds light on maleness

    A seven-year-old girl with a Y chromosome is providing new clues about a possible "master switch" of maleness.

    The girl has the normal chromosome count – 46 – and should be male. Other children who have the male sex chromosome but do not appear to be boys have been found to have gene mutations that temper the Y chromosome's effects. However this child doesn't have ambiguous gonads, shrivelled testes or other developmental defects. She instead has a normal vagina, cervix and set of ovaries.

    A team led by Anna Biason-Lauber, of University Children's Hospital in Zurich, Switzerland, thinks the patient's normalcy is due to mutations in a poorly understood gene on chromosome 17 called CBX2. . . .

    When a girl with normal sex organs was born, doctors started scratching their heads. Most females with a Y chromosome have underdeveloped gonads that are prone to developing tumours and usually removed. However, when surgeons operated with the intention of removing the gonads they found normal-looking ovaries in the girl, and took only a tissue sample. This sample, too, looked normal. (Source)
    This girl will likely lead a very confusing life, but I find it very cool. The CBX2 mutation prevented SRY from working normally, which prevented the male parts from developing.

    Wouldn't it be cool if she had a (viable) child that lacked an X chromosome?

    </madscientist>
    ...it's worse than we thought. it turns out the people at the white house are not secret muslims, they're nerds.

  2. #2
    Quote Originally Posted by Steven Edwards View Post
    Source:
    Girl with Y chromosome sheds light on maleness

    A seven-year-old girl with a Y chromosome is providing new clues about a possible "master switch" of maleness.

    The girl has the normal chromosome count – 46 – and should be male. Other children who have the male sex chromosome but do not appear to be boys have been found to have gene mutations that temper the Y chromosome's effects. However this child doesn't have ambiguous gonads, shrivelled testes or other developmental defects. She instead has a normal vagina, cervix and set of ovaries.

    A team led by Anna Biason-Lauber, of University Children's Hospital in Zurich, Switzerland, thinks the patient's normalcy is due to mutations in a poorly understood gene on chromosome 17 called CBX2. . . .

    When a girl with normal sex organs was born, doctors started scratching their heads. Most females with a Y chromosome have underdeveloped gonads that are prone to developing tumours and usually removed. However, when surgeons operated with the intention of removing the gonads they found normal-looking ovaries in the girl, and took only a tissue sample. This sample, too, looked normal. (Source)
    This girl will likely lead a very confusing life, but I find it very cool. The CBX2 mutation prevented SRY from working normally, which prevented the male parts from developing.

    Wouldn't it be cool if she had a (viable) child that lacked an X chromosome?

    </madscientist>
    Steven, a child without X-chromosomes would not survive. The X-chromosome contains essential genes. I don't think that the child will necessarily lead a very confusing life. A large number of children are born with so-called ambiguous genitalia and they are fixed. This child is clearly phenotypically female and normally so. Just because she carries a Y-chromosome is besides the point. It is her doctors who are surprised. I am actually a little surprised that the doctors who operated on her did not do an MRI first.

    Wise.

  3. #3
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    The XY sex-determination system is the sex-determination system found in humans, most other mammals, some insects (Drosophila) and some plants (Ginkgo). In this system, females have two of the same kind of sex chromosome (XX), and are called the homogametic sex. Males have two distinct sex chromosomes (XY), and are called the heterogametic sex.
    The XY sex determination system was first described independently by Nettie Stevens and Edmund Beecher Wilson in 1905.


    Mechanisms

    Some species (including most mammals) have a gene or genes on the Y chromosome that determine maleness. In the case of humans, a single gene (SRY) on the Y chromosome acts as a signal to set the developmental pathway towards maleness.[1] Other mammals use several genes on the Y chromosome for that same purpose. Not all male-specific genes are located on the Y chromosome.
    Other species (including most Drosophila species) use the presence of two X chromosomes to determine femaleness. One X chromosome gives putative maleness. The presence of Y chromosome genes are required for normal male development.
    Humans, as well as some other organisms, can have a chromosomal arrangement that is contrary to their phenotypic sex, that is, XX males or XY females. See, for example, XX male syndrome and Androgen insensitivity syndrome.

    I agree without the x chromosome no child can survive.
    http://en.wikipedia.org/wiki/XY_sex-...ination_system
    Something that is well diagnosed can be cured well."Hail Caesar! Those who are about to die salute you!" - Said by gladiators before they fought. Often cited with "salutamus" ("we . . . salute") in place of "salutant."

  4. #4
    Quote Originally Posted by Wise Young View Post
    Steven, a child without X-chromosomes would not survive. The X-chromosome contains essential genes. I don't think that the child will necessarily lead a very confusing life. A large number of children are born with so-called ambiguous genitalia and they are fixed. This child is clearly phenotypically female and normally so. Just because she carries a Y-chromosome is besides the point. It is her doctors who are surprised. I am actually a little surprised that the doctors who operated on her did not do an MRI first.

    Wise.
    Wise, I understand. I was just thinking that it would be cool if she was the first of a new breed of humans, where a disabled Y chromosome forms a semi-normal ovum (-X, +Y) that can be fertilized.

    Sci-fi instead of sci-fact.

    What would the MRI show?

    Steven
    ...it's worse than we thought. it turns out the people at the white house are not secret muslims, they're nerds.

  5. #5
    Senior Member Timaru's Avatar
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    Quote Originally Posted by Steven Edwards View Post
    Wise, I understand. I was just thinking that it would be cool if she was the first of a new breed of humans, where a disabled Y chromosome forms a semi-normal ovum (-X, +Y) that can be fertilized.

    Sci-fi instead of sci-fact.

    What would the MRI show?

    Steven
    What they found when they jumped in with both feet and an over eager scalpel?

  6. #6
    Quote Originally Posted by Steven Edwards View Post
    Wise, I understand. I was just thinking that it would be cool if she was the first of a new breed of humans, where a disabled Y chromosome forms a semi-normal ovum (-X, +Y) that can be fertilized.

    Sci-fi instead of sci-fact.

    What would the MRI show?

    Steven
    I agree with Timaru. It would have shown them a normal uterus and two normal ovaries. They could have then biopsied without having to go to surgery. The fact that they went in and were "surprised" by what they found is not good.

    Wise.

  7. #7
    XY females are normally caused by androgen insensitivity syndrome.

    Basically, using a computer analogy, the standard operating system for an embryo is to develop as female. However, if you have a Y chromosome the default kicks in at an early stage, when the embryo responds to the small amounts of testosterone they produce whilst in the uterus, testosterone being an androgen. However even though you have a Y chromosome, if you are insensitive to androgens the default operating system never kicks in so you continue to run the female operating system as you develop but becuase you lack a second X chromosome some of the vital female programmes are missing, like the internal female organs being absent. You look completely female but you have Y chromosome.
    Different olympics committees respond differently to this:

    Seven of the eight women who tested positive for Y chromosomes during the 1996 Atlanta Olympics had AIS. They were allowed to compete. Given the confusion and uncertainty over determining a person’s sex, the International Olympic Committee stopped gender testing in 1999. But the Olympic Council of Asia continues the practice.
    http://www.asianpacificpost.com/port...yclist.do.html

  8. #8
    Quote Originally Posted by Timaru View Post
    What they found when they jumped in with both feet and an over eager scalpel?
    I'm greatly distressed by the over eager scalpel mentality.

  9. #9
    What made them look more closely at this child? What had them questioning her chromosomal composition?

  10. #10
    There were rumors about the actress Jamie Lee Curtis having some form of this too.
    Nothing substantiated and no idea how it started.

    http://la.metblogs.com/2007/03/06/to...-teeny-weenie/

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