Title: Association of Clinical Features With Incidental Findings From Exome Sequencing in 3,223 African Americans
Description: Importance. The American College of Medical Genetics and Genomics recommends informing individuals who carry mutations in a set of Mendelian disease genes that might require clinical action regardless of genetic testing indication. However, whether such mutations lead to an increased risk for diseases in individuals not referred for clinical genetic testing has not been evaluated.

Objective. To evaluate whether those in the unselected general population who carry potentially actionable mutations are more likely to manifest the associated diseases than those without such mutations.

Design, Setting, and Participants. Cross-sectional observational study of participants enrolled in the Jackson Heart Study (Jackson, MS) between 2000 and 2004 who underwent whole exome sequencing (n = 3223). All participants were on African descent.

Exposures. Mutations across a set of 56 recommended clinically actionable genes ascertained by whole exome sequencing.

Main Outcomes and Measures. Evidence for pathogenicity for all mutations identified in 56 genes was determined by bioinformatic analyses and extensive literature review. Anticipated clinical findings for each of the 56 genes were extracted from study surveys, echocardiography, electrocardiography, and lipid panels across all participants without knowledge of mutation carrier status. The main outcome was the difference in expected clinical findings in those with mutations compared to those without.

Results. 3,223 African Americans had a total of 4,429 mutations across the 56 genes. Bioinformatic filters yielded 462 candidate pathogenic variants in 1945 participants (60%). Subsequent manual review of the evidence yielded 30 pathogenic variants in 44 (1.3 %) participants and 12 likely pathogenic variants in 23 (0.7 %). Participants with pathogenic or likely pathogenic variants were more likely to display suggested clinical features (19.6 %) compared with expected (7.1 %; one-sided P = 0.002) by a factor of 2.75 (95% CI , 1.37 to 4.92). In secondary analyses, the excess of observed clinical features was apparent in cardiovascular and cancer genes by 2.67-fold (95% CI, 1.07 to 5.51) and 2.89-fold (95% CI, 0.78 to 7.39), respectively.

Conclusions and Relevance. Unselected African Americans in the general population with pathogenic or likely pathogenic variants have an increased risk of displaying features associated with clinical disease.