Proficiency Testing of Standardized Samples Shows High Interlaboratory Agreement for Clinical Next-Generation Sequencing--Based Hematologic Malignancy Assays With Survey Material--Specific Differences in Variant Frequencies. - Keegan, Alissa; Bridge, Julia A.; Lindeman, Neal I.; Long, Thomas A.; Merker, Jason D.; Moncur, Joel T.; Montgomery, Nathan D.; Nagarajan, Rakesh; Rothberg, Paul G.; Routbort, Mark J.; Vasalos, Patricia; Xian, Rena; et al. (Archives of Pathology & Laboratory Medicine, 2020)