What is the difference between targeted testing and panel sequencing, and when is each used?

• A. Targeted testing looks for a known familial variant; panel sequencing sequences multiple genes.
• B. Targeted testing sequences multiple genes; panel sequencing searches for a single familial variant.
• C. Targeted testing analyzes noncoding regions; panel sequencing analyzes coding regions only.
• D. Targeted testing requires full genome sequencing to interpret results.

Answer: (A)

The main idea is choosing between testing for a single, known mutation versus testing many genes at once to look for possible disease-causing changes.

Targeted testing is used when a specific familial variant has already been identified in an affected relative or there is a strong likelihood from family history that a particular mutation is responsible. In this scenario, the test focuses on that one variant, making it faster, more cost-effective, and highly informative for confirming whether a family member carries that exact mutation.

Panel sequencing, on the other hand, looks across multiple genes at once that are known to be associated with a particular phenotype or syndrome. It’s used when the clinical picture could be due to mutations in several different genes, or when the family history doesn’t point to a single gene. This approach broadens the search and can increase the chance of finding the responsible genetic change, though it can yield variants that require careful interpretation.

So, the correct distinction is that targeted testing searches for a known familial variant, while panel sequencing sequences multiple genes to evaluate several possible culprits.