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How does the scaless gene work? (homozygous autosomal recessive Allel)

Discussion in 'General breed discussions & FAQ' started by RHRanch, Dec 16, 2011.

  1. RHRanch

    RHRanch Chillin' With My Peeps

    There is an auction for eggs from hens that may be (or are) carrying the scaless gene. Aparrently they are the hatchmates of the scaless naked rooster that the breeder no longer has. The auction is for 3 eggs from the hens. I want to know how the scaless gene works. Is it like when a bird is "split" for a recessive trait that needs 2 copies? If these hens have been bred to a NN rooster without the scaless gene, will the ofspring carry the scaless gene, what %? Can someone lay it out for me in laymans terms, with examples, or tell me anything about how the scaless gene works? I found a PDF that says the scaless genetic is: homozygous for an autosomal recessive allele. Does that help?

    I found this: Not sure if I understand what it means: There are two alleles that create the mutation of featherless chickens. One is the “naked neck” gene or (NA) and the scaleless gene (Sc), “The scaleless gene, at the homozygous recessive stage (sc/sc), eliminates the development of all feathers, thus producing completely naked chickens.” (departments.agri). These are two natural mutations that when combined create a featherless chicken. UC Davis was the first place to find the gene, “'In 1954, the American researchers Abbott and Asmundson found several featherless mutants among New Hampshire chicks that hatched at the University of California at Davis. The mutation, named “Scaleless”, has been bred and maintained since then in.”

    The breeder says that if you breed 2 carriers of the gene together you get about 2% naked (scaless) chicks. Is that really the % you would expect?
     
    Last edited: Dec 16, 2011
  2. tadkerson

    tadkerson Chillin' With My Peeps

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    Genetics 101

    Normally if two organisms are crossed and each one carries an autosomal recessive gene for a trait, then statistically one in four of the offspring (25%) should express the trait.

    If only 2% of the offspring express the trait, then their are two possibilities: 1. the trait requires one or more other genes to be expressed 2. the genes do not express the trait in every organism- this is called reduced penetrance.
     
  3. RHRanch

    RHRanch Chillin' With My Peeps

    Quote:Thank you - That is how I understood the autosomal recessive genes to work, which is why I was confused about the 2%. Humm....
     

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