Palomaki GE, Wyatt P, Best RG, Lepage N, Ashwood ER, Souers RJ, Thorson JA. Assessment of laboratories offering cell-free (cf) DNA screening for Down syndrome: results of the 2018 College of American Pathology External Educational Exercises.
Genet Med 2020;
22:777-784. [PMID:
31929509 DOI:
10.1038/s41436-019-0718-4]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 11/22/2019] [Indexed: 11/09/2022] Open
Abstract
PURPOSE
Summarize and interpret results from exercises distributed to laboratories offering cell-free (cf) DNA screening for Down syndrome.
METHODS
The College of American Pathologists distributed three patient-derived plasma specimens twice in 2018. Sequencing platforms, test methods, results, and responses to supplemental questions were collected. Results were not graded but discrepancies were identified.
RESULTS
Sixty-five laboratories from six continents enrolled; six provided no results. The most common methodology was shotgun/genome sequencing (39/56, 70%). Overall, 40% of the gestational or maternal age responses were incorrect but 45% of the errors were corrected by the next distribution. Fetal fractions from 54 responding laboratories generally agreed with the intended response. No genotyping errors occurred (40/40 for trisomy 21 and 226/226 for euploid challenges) but 10 additional tests failed (3.6%). All 213 fetal sex calls were correct. Participants reported their clinical text for a Down syndrome screen positive test; 39% were classified as inadequate or misleading.
CONCLUSION
Patient-derived materials are suitable for all enrolled technologies/methodologies, but collecting material is challenging. Suggested clinical text includes the terms "screen positive" and "screen negative." Overall, laboratories performed well. Future efforts will focus on potential manufactured samples, clarifying results reporting and including additional chromosome abnormalities.
Collapse