A pathogenic gene is a gene containing a specific change in its DNA sequence (a variant) that increases the risk of developing a particular disease or disorder, such as cancer.
Understanding Pathogenic Genes
Pathogenic variants (or mutations) disrupt the normal function of a gene, leading to disease. Here's a more detailed breakdown:
- Gene: A segment of DNA that contains instructions for making a specific protein.
- Variant (Mutation): A change in the DNA sequence of a gene. Not all variants are harmful; some are neutral, and some can even be beneficial.
- Pathogenic: Describes a variant that causes or increases the risk of disease.
How Pathogenic Variants Arise
Pathogenic variants can be inherited or acquired:
- Inherited (Germline) Variants: Passed down from a parent to their child. These variants are present in every cell of the body.
- Acquired (Somatic) Variants: Occur during a person's lifetime. They are caused by factors like exposure to radiation or errors during DNA replication. These variants are only present in certain cells. Cancer is a disease that often involves somatic mutations in genes controlling cell growth and division.
Examples of Pathogenic Genes
Certain genes are well-known for having pathogenic variants associated with specific diseases:
- BRCA1 and BRCA2: Pathogenic variants in these genes significantly increase the risk of breast and ovarian cancer.
- CFTR: Pathogenic variants in this gene cause cystic fibrosis.
- Huntingtin (HTT): A pathogenic variant (specifically, an expanded CAG repeat) in this gene causes Huntington's disease.
Clinical Significance
Identifying pathogenic variants is crucial for:
- Diagnosis: Determining the underlying cause of a genetic disorder.
- Risk Assessment: Assessing an individual's likelihood of developing a disease.
- Personalized Medicine: Tailoring treatment strategies based on an individual's genetic makeup.
- Genetic Counseling: Helping individuals and families understand the risks of inheriting or passing on a genetic disorder.
In conclusion, a pathogenic gene carries a DNA sequence variant that can cause or increase the risk of a particular disease, which has significant implications for diagnosis, risk assessment, and personalized medicine.
