Gene variants, previously known as gene mutations, work by altering the DNA sequence of a gene, potentially changing the protein it produces and its function.
Here's a more detailed breakdown:
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What is a Gene Variant? A gene variant is a permanent change in the DNA sequence that makes up a gene. These changes can occur spontaneously or be inherited. While the term "mutation" was previously used, "variant" is now favored because not all DNA changes lead to disease.
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How DNA Changes Occur: Gene variants arise from a variety of sources, including:
- Errors during DNA replication: When DNA is copied during cell division, mistakes can occur.
- Exposure to mutagens: Environmental factors like radiation and certain chemicals can damage DNA.
- Inherited variants: Parents can pass down gene variants to their offspring.
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Impact on Protein Production: The sequence of DNA in a gene provides instructions for building a specific protein. Gene variants can alter this sequence in different ways:
- Substitution: One DNA base is replaced by another. This can lead to a different amino acid being incorporated into the protein, potentially changing its structure and function.
- Insertion: Extra DNA bases are added to the gene sequence. This can disrupt the reading frame of the gene, leading to a completely different protein or a non-functional one.
- Deletion: DNA bases are removed from the gene sequence. Similar to insertions, deletions can shift the reading frame and alter the protein.
- Frameshift: Insertions or deletions that are not multiples of three bases cause a shift in the reading frame of the gene.
- Duplication: A segment of DNA is copied multiple times. This can lead to an overproduction of the protein.
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Consequences of Gene Variants: The impact of a gene variant depends on several factors, including:
- The specific gene affected: Some genes are more critical than others.
- The type of variant: Some variants have a larger effect than others.
- The location of the variant within the gene: Variants in certain regions of a gene (e.g., the active site of an enzyme) may have a more significant impact.
- Whether the variant is in a coding or non-coding region: Variants in non-coding regions can still affect gene expression.
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Outcomes of a Variant:
- No Effect: Some gene variants have no noticeable effect on health or development. These are often called "neutral" variants.
- Beneficial Effect: Rarely, a gene variant may provide a benefit, such as increased resistance to a disease.
- Harmful Effect: Many gene variants can cause or increase the risk of diseases, such as genetic disorders, cancer, and other complex conditions.
In summary, gene variants work by changing the DNA sequence of a gene, potentially altering the protein it produces and affecting its function. The consequences of a gene variant can range from having no effect to causing significant health problems.
