What is the primary genetic alteration associated with familial adenomatous polyposis (FAP)?

What is the primary genetic alteration associated with familial adenomatous polyposis (FAP)?

• A. Biallelic loss of function of the BRCA gene
• B. Biallelic loss of function of the APC gene
• C. Biallelic loss of function of the KRAS gene
• D. Biallelic loss of function of the TP53 gene

Answer: (B)

Familial adenomatous polyposis (FAP) is primarily associated with mutations in the APC (Adenomatous Polyposis Coli) gene. This gene is a tumor suppressor located on chromosome 5. In individuals with FAP, a germline mutation leads to a biallelic loss of function—meaning that both alleles of the gene are affected—resulting in a failure to properly regulate cell growth and proliferation. The APC gene plays a crucial role in the Wnt signaling pathway, which is involved in controlling the development of cells in the colon. When the APC gene is mutated, it can lead to the formation of numerous polyps in the colon and rectum, which have a high potential to progress to colorectal cancer if left untreated. The identification of biallelic loss of function in the APC gene is essential for the diagnosis of FAP and for understanding the hereditary nature of the disease, as it is passed down in an autosomal dominant manner. This understanding is fundamental for genetic counseling, surveillance, and management strategies for individuals and families affected by this condition.

Familial adenomatous polyposis (FAP) is primarily associated with mutations in the APC (Adenomatous Polyposis Coli) gene. This gene is a tumor suppressor located on chromosome 5. In individuals with FAP, a germline mutation leads to a biallelic loss of function—meaning that both alleles of the gene are affected—resulting in a failure to properly regulate cell growth and proliferation.

The APC gene plays a crucial role in the Wnt signaling pathway, which is involved in controlling the development of cells in the colon. When the APC gene is mutated, it can lead to the formation of numerous polyps in the colon and rectum, which have a high potential to progress to colorectal cancer if left untreated. The identification of biallelic loss of function in the APC gene is essential for the diagnosis of FAP and for understanding the hereditary nature of the disease, as it is passed down in an autosomal dominant manner.

This understanding is fundamental for genetic counseling, surveillance, and management strategies for individuals and families affected by this condition.