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    what is haemophilia?

    Why does a carrier not suffer from the disease?

    just any helpful pointers or an explanation would be fantastic, many thanks
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    means your blood doesn't clot very well. this might help:

    http://en.wikipedia.org/wiki/Haemophilia
    http://www.bbc.co.uk/health/physical...ophilia1.shtml
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    (Original post by annaacer)
    what is haemophilia?

    - Haemophilia is where the body lacks a specific clotting factor causing the blood to clot more slowly or not in the correct way. Different types of haemophilia having different clotting factors missing, I.E the clotting factor missing in haemophilia A is not the same as the clotting factor missing in haemophilia B.

    Why does a carrier not suffer from the disease?

    - Haemophilia is a recessive genetic disease. This means that if a person has one normal gene and one gene that causes haemophilia, the normal gene is essentially "more powerful" and thus provides a normal effect on the person. A carrier is someone who has the gene in their DNA but does not have the disease. This indicates that they have one normal gene and one haemophilia causing gene and due to the effect described above of the normal gene being "more powerful" they thus do not have the disease.

    why does a daughter have a 50/50 chance of being a carrier but a son have a 50/50 chance of having the condition?

    - Haemophilia is a X chromosome disorder. This means that the disease is passed through the family via the X chromosome. The Chromosome make up of women is XX but males are XY and thus since females have twice as many X chromosomes and it is a recessive disease females have a reduced chance of getting haemophilia. It should also be noted that the chance will change depending on whether the parents are carriers or actually have the condition.

    With reference to chromosomes, why could a female haemophiliac be produced from a female and male carrier?

    - A female donates an X chromosome to a child. A male also donates an X chromosome to a female child. If both parents are carriers that means that both parents have one normal gene and one haemophilia causing gene. Since a parent only donates one gene the daughter can either get two normal genes (25% chance), one normal gene and one haemophilia causing gene (50% chance) or two haemophilia causing genes (25% chance), this happens for both X chromosomes and thus there is a possibility that the daughter may get two haemophilia causing genes on both X chromosomes and thus be a haemophiliac.

    just any helpful pointers or an explanation would be fantastic, many thanks
    See the bold comments.
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    (Original post by annaacer)
    With reference to chromosomes, why could a female haeomphiliac be produced from a female and male carrier?
    Just a small point - there's no such thing as a male carrier, males can only be sufferers.
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    (Original post by Revd. Mike)
    Just a small point - there's no such thing as a male carrier, males can only be sufferers.
    Is this due to the X chromosome? Haven't read other comments sorry
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    it probably means your a long lost member of the Romonov family who ruled R|ussia up to the glorious revolution, hand yourself in and we will have you topped like the rest of them. All we need to do is prick your finger, nature will do the rest!
    RASPUTIN!
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    (Original post by Des the bluenose)
    it probably means your a long lost member of the Romonov family who ruled R|ussia up to the glorious revolution, hand yourself in and we will have you topped like the rest of them. All we need to do is prick your finger, nature will do the rest!
    RASPUTIN!
    Damn, I was about to make a Romanov reference.
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    In haemophilia, the blood's ability to clot is severely reduced because an essential clotting factor - a chemical within the blood - is partly or completely missing. This means that people bleed for longer than normal.

    Theres two different types of Haemophilia:

    Haemophilia A - a deficiency of an essential clotting factor called factor VIII, which is normally produced in the liver. The faulty gene that causes haemophilia A is found on the X chromosome (X-linked). The faulty gene is found on the X chromosome (X-linked). It's five times more common than haemophilia B.

    Haemophilia B - a deficiency of clotting factor IX and also X-linked. Quite often there is no family history and the disorder is a new development because of a new genetic mutation.

    Male have XY chromosomes
    Female have XX chromosomes (so more of a chance that they will be carrier?)

    Im not sure about why males would more likely have the condition
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    With reference to chromosomes, why could a female haeomphiliac be produced from a female and male carrier?

    mother (carrier) - XX
    father (sufferer) - XY

    daughter would either be:
    - carrier XX
    or
    - sufferer XX

    ^^
    this is the correct anwser. HTH
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    (Original post by Eloades11)
    Is this due to the X chromosome? Haven't read other comments sorry
    Indeed, the gene is recessive and found on the X chromosome. Females having two X chromosomes means that both would have to have the mutant gene in order for her to be affected. Males only have one X chromosome, so if they inherit the mutant gene they'll invariably be affected because they don't have another X chromosome with a WT gene to compensate.
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    (Original post by Revd. Mike)
    Indeed, the gene is recessive and found on the X chromosome. Females having two X chromosomes means that both would have to have the mutant gene in order for her to be affected. Males only have one X chromosome, so if they inherit the mutant gene they'll invariably be affected because they don't have another X chromosome with a WT gene to compensate.
    Thats good to understand, thanks
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    I have only been here for all of 20 seconds and I have already came to the conclusion that;

    50%? of the people, threads and posts here are full of idiots who have seem to have forgot what google is for.

    http://en.wikipedia.org/wiki/Haemophilia
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    (Original post by Bi0logical)
    Theres two different types of Haemophilia
    Theres actually more than two types of haemophilia not to mention other similar diseases such as Von Willebrands Disease.
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    (Original post by annaacer)
    what is haemophilia?

    Why does a carrier not suffer from the disease?

    just any helpful pointers or an explanation would be fantastic, many thanks
    hemophilia congenital tendency to uncontrolled bleeding, usually affects males and is transmitted from mother to son
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    (Original post by Revd. Mike)
    Indeed, the gene is recessive and found on the X chromosome. Females having two X chromosomes means that both would have to have the mutant gene in order for her to be affected. Males only have one X chromosome, so if they inherit the mutant gene they'll invariably be affected because they don't have another X chromosome with a WT gene to compensate.
    Wouldnt that mean males should only be carriers since they can never have two of the recessive gene responsible for haemophilia.
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    (Original post by Core)
    Wouldnt that mean males should only be carriers since they can never have two of the recessive gene responsible for haemophilia.
    Not quite When thinking of recessive and dominant alleles, don't think of it as you need two recessives to make the phenotype, but more that the dominant allele overshadows the effect of the dominant one. (This is a bit of an over-simplification, but a useful way to think about it at this level).

    The Y chromosome has few genes on it, and different ones to the X chromosome, so if a male has one X chromosome with the recessive haemophilia allele, they won't have the healthy dominant allele to shield them from the disease.
 
 
 
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