Mayo Clinic has launched a first-of-its-kind clinical test that will be used to help patients who may be at a diagnostic “dead end” with other genetic testing. The mate-pair sequencing test can identify chromosome alterations or “breakpoints” involved in chromosome rearrangements, pinpointing the precise genes involved. “Until now, this type of test was not available for clinical use,” says Robert Jenkins, M.D., Ph.D., a Mayo Clinic pathologist and cancer geneticist. “The assay can be really useful in knowing which genes are at those breakpoints because current chromosome studies cannot provide that level of resolution.” The new test examines all 23 pairs of chromosomes in a single test and could help clinicians and patients avoid unnecessary and potentially expensive extra tests when searching for a chromosome abnormality. In addition, because the test looks at all chromosomes, it may be able to identify previously unknown alterations that may provide patients with a diagnosis or possibly change their treatment. The test is available to Mayo Clinic patients and health care providers worldwide through Mayo Medical Laboratories, the global reference laboratory of Mayo Clinic. Nicole Lynn Hoppman, Ph.D., a Mayo Clinic molecular cytogeneticist who focuses on testing and research of congenital disorders, says, “It can be emotionally difficult for families to go on a medical journey and never really arrive at an explanation. This test offers earlier answers for young patients with neurological or developmental delays who have been part of a diagnostic odyssey.” Cancer researchers say this test is especially useful for understanding the underlying biology of a patient’s tumor. Knowing the nature of the gene rearrangement could change the way an individual’s cancer is managed. “Being able to put disease types into diagnostic categories is important to patients,” says Dr. Jenkins. George Vasmatzis, Ph.D., a Mayo Clinic genomicist, is the primary developer of the software and experimental procedures that led to the new test. Dr. Vasmatzis co-directs the Biomarker Discovery Program within the Mayo Clinic Center for Individualized Medicine along with John Cheville, M.D., a Mayo Clinic pathologist. “Our mate-pair sequencing technology is transformative, allowing genomic information critical to patient care to be determined comprehensively, accurately and quickly,” says Dr. Vasmatzis. “Our program is working closely with the Mayo Clinic Medical Genome Facility and the Department of Laboratory Medicine and Pathology to explore additional mate-pair next-generation sequencing applications.” This work was supported by the Mayo Clinic Center for Individualized Medicine and the Mayo Clinic Department of Laboratory Medicine and Pathology. About the mate-pair sequencing test (Test IDs: MTRBL, MTRTI, and MTRBM) For congenital chromosome abnormalities, the mate-pair sequencing test is appropriate for individuals with an apparently balanced congenital chromosome rearrangement of uncertain clinical significance. For oncologic and hematologic specimens, the mate-pair sequencing test is appropriate for individuals with previously detected acquired chromosomal abnormalities. This next-generation sequencing technology can aid in the further characterization of chromosome abnormalities by sequencing the entire genome and creating a structural map of the genome. The technique enables the detection of chromosome rearrangements, which allows for determination of genes at or near the breakpoints.