Percentage of colonies positive for variant in methylcellulose colony-forming assays on 3 samples with reference variants determined from a concurrent RHP on a separate specimen. PB methylcellulose colony-forming assays were performed on 3 samples with reference variants determined from a concurrent peripheral blood specimen (sample A) or concurrent or recent BM sample (samples B and C). Six colonies were obtained for sample A, and 10 colonies were obtained for samples B and C after 9 days in culture.