Abbi asked in Science & MathematicsBiology · 8 years ago

How/why are mutations that cause genetic disorders maintained in a population?

How/why are mutations that cause genetic disorders maintained in a population?

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  • Caitie
    Lv 7
    8 years ago
    Favorite Answer

    Mutations that are positive and help the population survive better are obviously passed on to the offspring and are plentiful.

    The issue is, why don't lethal genes eventually die off? Because, even though harmful or even lethal genes can kill the organism before it has a chance to reproduce, these genes are still carried by normal members of the population since almost all of them are recessive. Therefore, they stay in the population. Also, random mutations, which do occur in every population, keep these genes in the pool. Cystic fibrosis, for example, is a lethal gene in the human population, but it can be carried without being expressed because it is recessive, so it remains in the population "hiding out" until it is paired with another CF allele and, a CF person is born and has a very short life span. Also, CF alleles randomly mutate into the population.

    I know it seems strange and illogical, but even lethal alleles never completely disappear from a population, mainly because they are almost always recessive and even if they are not, random mutations occur anyway.

    Source(s): retired AP biology teacher, masters, human physiology
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  • Todd
    Lv 7
    8 years ago

    This happens when the mutations are not debilitating enough to prevent procreation. For humans and many other mammals, debilitation includes not only physical traits, but also social ones, which depends on a variety of factors. In other words, traits that the environment - the whole enchilada - doesn't all together remove from the gene pool stick around.

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