Final answer:
The molecular phenotype associated with hereditary nonpolyposis colon cancer is Microsatellite instability, resulting from impaired DNA mismatch repair and leading to an increased risk of colorectal and other types of cancer.
Step-by-step explanation:
Heredity and Cancer
The molecular phenotype associated with hereditary nonpolyposis colon cancer (HNPCC), also known as Lynch syndrome, is C. Microsatellite instability (MSI). MSI is a condition of genetic hypermutability that results from impaired DNA mismatch repair (MMR). In HNPCC, mutations occur in the MMR genes, leading to the accumulation of errors throughout the genome, particularly affecting microsatellite regions, which are short, repeated sequences of DNA.
When MMR is deficient, the cell's ability to correct mistakes during DNA replication is compromised, allowing mutations to accumulate. Such mutations can lead to uncontrolled cell division and tumor development. Patients with HNPCC are at a higher risk of developing colorectal cancer and other types of cancer due to this increased mutation rate in their genomes.