How do exome and genome sequencing differ in reporting incidental findings?

• A. Exome sequencing has a larger potential for incidental findings.
• B. Genome sequencing has a larger potential for incidental findings.
• C. Both have no incidental findings.
• D. Incidental findings are only reported for genome sequencing.

Answer: (B)

Incidental findings are unexpected results unrelated to why the test was ordered but that could have health implications. Genome sequencing looks at the entire genome, including coding and noncoding regions, so it generates vastly more data and a wider range of variants than exome sequencing, which targets only the protein-coding exons. With the broader scope, there are more opportunities to uncover clinically meaningful variants that were not the target of the test, leading to a higher potential for incidental findings. Because of this greater breadth, genome sequencing carries a larger chance of revealing incidental information. Reporting of these findings also depends on consent and guidelines (such as ACMG recommendations), but the fundamental reason the potential is greater with genome sequencing is simply the expanded genomic territory it covers.