Understanding Autosomal Dominant and Autosomal Recessive Inheritance

Zero To Finals2 minutes read

Mendelian inheritance involves autosomal recessive and dominant conditions, where one abnormal gene on non-sex chromosomes causes diseases like Huntington's and cystic fibrosis. Risk of passing on recessive conditions is 25% for disease, 50% for carrier, and 25% for normal genes, while for dominant conditions, it's a 50% chance if one parent has the gene, and 50% for normal genes if both parents are disease-free.

Insights

  • Mendelian inheritance includes autosomal recessive and autosomal dominant conditions, where a single abnormal gene on non-sex chromosomes leads to genetic diseases like Huntington's chorea and cystic fibrosis.
  • In autosomal dominant conditions, having one copy of the disease gene is sufficient to express the disease, whereas in autosomal recessive conditions, both gene copies must be disease genes for the condition to manifest.

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Recent questions

  • What is Mendelian inheritance?

    Mendelian inheritance involves the passing of genetic traits from parents to offspring through single genes on non-sex chromosomes.

  • How does autosomal dominant inheritance work?

    Autosomal dominant conditions like Huntington's chorea only require one copy of the disease gene to express the condition.

  • How does autosomal recessive inheritance differ?

    Autosomal recessive conditions like cystic fibrosis need both copies of the gene to be disease genes for the condition to manifest.

  • What is the risk of passing on an autosomal recessive condition?

    Carriers of autosomal recessive conditions have one disease gene and one normal gene, leading to a 25% chance of disease, carrier, or normal genes in offspring.

  • How does the presence of disease genes in parents affect offspring?

    If one parent has the disease gene for an autosomal dominant condition, there is a 50% chance of passing it on, while if both parents are disease-free, there is a 50% chance of having normal genes.

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Summary

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Genetic Inheritance: Dominant and Recessive Conditions

  • Mendelian inheritance involves the inheritance of autosomal recessive and autosomal dominant conditions, where a single abnormal gene on non-sex chromosomes causes certain genetic diseases like Huntington's chorea and cystic fibrosis.
  • In autosomal dominant conditions like Huntington's chorea, having just one copy of the disease gene is enough to express the disease, while in autosomal recessive conditions like cystic fibrosis, both copies of the gene must be disease genes to manifest the condition.
  • Calculating the risk of passing on an autosomal recessive condition involves understanding that carriers have one disease gene and one normal gene, leading to four possible outcomes in offspring: disease, carrier, or normal genes, with a 25% chance of each.
  • For autosomal dominant conditions, if one parent has the disease gene, there is a 50% chance of passing on the disease to offspring, while if both parents are disease-free, there is a 50% chance of having normal genes.
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