Outcome of Whole Exome Sequencing for Diagnostic Odyssey Cases of an Individualized Medicine Clinic: The Mayo Clinic Experience

Objective To describe the experience and outcome of performing whole-exome sequencing (WES) for resolution of patients on a diagnostic odyssey in the first 18 months of an individualized medicine clinic (IMC). Patients and Methods The IMC offered WES to physicians of Mayo Clinic practice for patients with suspected genetic disease. DNA specimens of the proband and relatives were submitted to WES laboratories. We developed the Genomic Odyssey Board with multidisciplinary expertise to determine the appropriateness for IMC services, review WES reports, and make the final decision about whether the exome findings explain the disease. This study took place from September 30, 2012, to March 30, 2014. Results In the first 18 consecutive months, the IMC received 82 consultation requests for patients on a diagnostic odyssey. The Genomic Odyssey Board deferred 7 cases and approved 75 cases to proceed with WES. Seventy-one patients met with an IMC genomic counselor. Fifty-one patients submitted specimens for WES testing, and the results have been received for all. There were 15 cases in which a diagnosis was made on the basis of WES findings; thus, the positive diagnostic yield of this practice was 29%. The mean cost per patient for this service was approximately $8000. Medicaid supported 27% of the patients, and 38% of patients received complete or partial insurance coverage. Conclusion The significant diagnostic yield, moderate cost, and notable health marketplace acceptance for WES compared with conventional genetic testing make the former method a rational diagnostic approach for patients on a diagnostic odyssey.