The inheritance of certain mutations of BRCA1 can make it much more likely that a woman will develop breast or ovarian cancer in her lifetime. Can you say with certainty that a woman inheriting a mutation of BRCA1 will definitely develop breast or ovarian cancer in her lifetime? Why or why not?

Key Concepts

BRCA1 Gene Function

The BRCA1 gene is crucial for repairing DNA breaks and maintaining genomic stability. Mutations in this gene can impair its function, leading to an increased risk of cancer, particularly breast and ovarian cancers. Understanding the role of BRCA1 in cellular processes helps explain why its mutations are linked to higher cancer susceptibility.

Genetic Predisposition vs. Certainty

Genetic predisposition refers to an increased likelihood of developing a condition based on inherited genetic factors. However, inheriting a mutation does not guarantee that an individual will develop the associated disease, as other factors such as environmental influences and lifestyle choices also play significant roles in cancer development.

Penetrance and Expressivity

Penetrance is the proportion of individuals with a specific genotype who exhibit the associated phenotype, while expressivity refers to the degree to which a genotype is expressed in an individual. For BRCA1 mutations, the penetrance can vary, meaning that not all women with the mutation will develop breast or ovarian cancer, and those who do may experience different severities of the disease.