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Inbreeding impact on Y chromosome?

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  • Zaru
    replied
    Thank you Ann!

    Originally posted by Ann Turner View Post
    No, inbreeding is not relevant for the Y chromosome. The reference to paternal and maternal in the intro pertains to chromosomes 1-22 (and the X chromosome in females). Homogeneity means that the child is more likely to inherit the same DNA fragment from a grandparent, since both the father and the mother can pass it on to the child.

    The child of first cousins would have more markers that are "homozygous" on the Family Finder test. This only matters if the DNA fragment in the grandparent already has a harmful mutation. Inbreeding per se does not increase the mutation rate (although I suppose there might be a gene that influences the mutation rate).
    I appreciate that clarification. I am having a very difficult time sorting through a large lot of distinct and different NPE within our surname group. I think that Occam's Razor may be upon me.

    Leave a comment:


  • Zaru
    replied
    Cheers.

    Originally posted by Javelin View Post
    No, just trying to understand what you mean. The Y can be affected by inbreeding at a population level (drift as Ann outlines), but not at an individual level.
    I really don't understand what it is that I mean! I am seeking substantive rationale for a whole slew of Y differentials in our surname project. The obvious answer is NPE. So I am seeking out other plausible solutions in order to be precise.

    So, it appears that inbreeding does not affect Y mutation rates. Is there anything that COULD (at a GD=15) in a 400 year period and still reconcile with the same MRCA?

    Cheers.

    Leave a comment:


  • Ann Turner
    replied
    Originally posted by Zaru View Post
    That's not the entirety of the study though. It also discusses the impact that inbreeding has genetically on individuals as expressed in the intro:

    "The study of inbreeding, the consequence of mating with relatives, has an important place in genetics.The similarity of the paternal and maternal contributions caused by the mating of relatives leads to increased homogeneity of inbred individuals."

    I am not maintaining that Y is affected in inbreeding, I am only asking if it is possible.

    Cheers.
    No, inbreeding is not relevant for the Y chromosome. The reference to paternal and maternal in the intro pertains to chromosomes 1-22 (and the X chromosome in females). Homogeneity means that the child is more likely to inherit the same DNA fragment from a grandparent, since both the father and the mother can pass it on to the child.

    The child of first cousins would have more markers that are "homozygous" on the Family Finder test. This only matters if the DNA fragment in the grandparent already has a harmful mutation. Inbreeding per se does not increase the mutation rate (although I suppose there might be a gene that influences the mutation rate).

    Leave a comment:


  • mixedkid
    replied
    Originally posted by Zaru View Post
    Does inbreeding have an impact on mutation rates for the Y chromosome? The parents in question were first cousins.

    Cheers,

    Rosario
    I've never heard of any study that would point towards that happening. However, I think I understand the thought behind your immediate question: Does the occurrence of repeated inbreeding affect mutation rates of not only the Y chromosome but of any chromosome? Perhaps it does. Perhaps there is a mechanism that geneticists don't know about yet that is triggered by inbreeding -- a mechanism that is set in motion to create genetic variation which is more advantageous to the organism in question (a human being), even in an isolated or small breeding population. Genes on different chromosomes do communicate with one another. Perhaps those communication lines have an effect on mutation rates. Overall then, it might be a very natural, biological, built-in protection mechanism.

    Leave a comment:


  • Javelin
    replied
    Originally posted by Zaru View Post
    You are coming across as being condescending. I hope that is not your purpose
    No, just trying to understand what you mean. The Y can be affected by inbreeding at a population level (drift as Ann outlines), but not at an individual level.

    Leave a comment:


  • Zaru
    replied
    Thank you for your response.

    Originally posted by Ann Turner View Post
    The linked paper is not talking about mutations or mutation rates. It's talking about a process called genetic drift, which applies to populations. For example, suppose two villages both start out with 40% of the people having blood type A. After one hundred years of marriages within their own village, 55% of the people in one village might have blood type A, while 34% of the people in the other village have blood type A. The percentages have drifted away from the starting point. This is just a random change, depending on how many children happened to be born to parents with blood type A compared to other blood types.
    That's not the entirety of the study though. It also discusses the impact that inbreeding has genetically on individuals as expressed in the intro:

    "The study of inbreeding, the consequence of mating with relatives, has an important place in genetics.The similarity of the paternal and maternal contributions caused by the mating of relatives leads to increased homogeneity of inbred individuals."

    I am not maintaining that Y is affected in inbreeding, I am only asking if it is possible.

    Cheers.

    Leave a comment:


  • Ann Turner
    replied
    Originally posted by Zaru View Post
    My question is whether or not an inbreeding scenario could cause a quicker mutation rate on any loci as a result of the event? The linked paper caused confusion for me.
    The linked paper is not talking about mutations or mutation rates. It's talking about a process called genetic drift, which applies to populations. For example, suppose two villages both start out with 40% of the people having blood type A. After one hundred years of marriages within their own village, 55% of the people in one village might have blood type A, while 34% of the people in the other village have blood type A. The percentages have drifted away from the starting point. This is just a random change, depending on how many children happened to be born to parents with blood type A compared to other blood types.

    Leave a comment:


  • Zaru
    replied
    Originally posted by Javelin View Post
    If a mother has no Y, how is her relatedness to the father supposed to affect the Y's mutation rates?
    You are coming across as being condescending. I hope that is not your purpose as I am trying to grasp the science, which as we all know is not terribly simple. If you peruse the linked paper then you will understand my question.
    Last edited by Zaru; 4 November 2011, 05:36 PM.

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  • Javelin
    replied
    If a mother has no Y, how is her relatedness to the father supposed to affect the Y's mutation rates?

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  • Zaru
    replied
    Originally posted by Javelin View Post
    Do you mean something like "rates or variation in the Y chromosome in a population" rather than "one individual's Y"?
    Not exactly, but they would be symbiotic, no?

    My question is whether or not an inbreeding scenario could cause a quicker mutation rate on any loci as a result of the event? The linked paper caused confusion for me.

    Leave a comment:


  • Javelin
    replied
    Do you mean something like "rates or variation in the Y chromosome in a population" rather than "one individual's Y"?

    Leave a comment:


  • Zaru
    replied
    Originally posted by k.o.gran View Post
    Hi Rosario,

    As the mother does not carry the Y-chromosome, I can't see how it could be affected in that scenario.

    -Kai
    I became quite confused upon reading this study by Cavalli-Sforza:


    http://books.google.com/books?id=XBH...mosome&f=false

    Leave a comment:


  • k.o.gran
    replied
    Originally posted by Zaru View Post
    Does inbreeding have an impact on mutation rates for the Y chromosome? The parents in question were first cousins.
    Hi Rosario,

    As the mother does not carry the Y-chromosome, I can't see how it could be affected in that scenario.

    -Kai

    Leave a comment:


  • Zaru
    started a topic Inbreeding impact on Y chromosome?

    Inbreeding impact on Y chromosome?

    Does inbreeding have an impact on mutation rates for the Y chromosome? The parents in question were first cousins.

    Cheers,

    Rosario
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