What are founder mutations?

What are founder mutations?

• A. Founder mutations are recurrent pathogenic variants in a population due to ancestry; testing can be targeted to common variants in those groups to improve efficiency.
• B. Mutations that occur spontaneously in each generation.
• C. Mutations confined to a single family with no population implication.
• D. Mutations that only affect non-coding regions.

Answer: (A)

Founder mutations come from a common ancestor within a specific population and are passed down through generations. Because they originated in a small group that expanded, the same pathogenic variant can be carried by many descendants, making it more frequent in that population than in others. In hereditary cancer risk testing, this allows a targeted approach: screening for a set of known founder mutations common in that ancestry often catches most cases efficiently and cost-effectively. If those are negative but risk remains high, broader sequencing can still identify other variants. This concept is different from mutations that arise anew in each generation (de novo), or those confined to a single family with no population-level impact, and it isn’t about whether a mutation lies in coding or non-coding regions—the defining feature is its higher frequency due to shared ancestry in a population. For example, certain BRCA1/BRCA2 founder mutations are well known in specific ethnic groups.

Founder mutations come from a common ancestor within a specific population and are passed down through generations. Because they originated in a small group that expanded, the same pathogenic variant can be carried by many descendants, making it more frequent in that population than in others. In hereditary cancer risk testing, this allows a targeted approach: screening for a set of known founder mutations common in that ancestry often catches most cases efficiently and cost-effectively. If those are negative but risk remains high, broader sequencing can still identify other variants. This concept is different from mutations that arise anew in each generation (de novo), or those confined to a single family with no population-level impact, and it isn’t about whether a mutation lies in coding or non-coding regions—the defining feature is its higher frequency due to shared ancestry in a population. For example, certain BRCA1/BRCA2 founder mutations are well known in specific ethnic groups.