What is the risk associated with the I1307K variant in the Ashkenazi Jewish population?

The I1307K variant is associated with an increased risk of colorectal cancer but is considered to confer a lower risk compared to classic Familial Adenomatous Polyposis (FAP). Individuals with classic FAP typically have a nearly 100% risk of developing colorectal cancer by the age of 40 if the condition is not treated, due to the presence of numerous polyps throughout the colon. In contrast, the I1307K variant increases the risk of colorectal cancer to a certain extent, but this risk is significantly lower than that associated with classic FAP.

In the Ashkenazi Jewish population, the prevalence of the I1307K variant and its association with a moderate risk of colorectal cancer has been well-studied. However, it does not lead to the same level of certainty or early onset risk as classic FAP. Consequently, individuals with the I1307K variant can benefit from increased screening and surveillance, but they do not face the same immediate and severe risk posed by those with classic FAP. This distinction is crucial in framing risk assessment and management strategies for individuals carrying the variant in question.