Down-sampling to balance sets of specific tumour types was pursued only when the average F1 score improved by over 5%, as applied to ARID1A, ASXL1, BRAF, BRCA1, CDK12, CTNNB1, KEAP1, MTOR, NOTCH1, PBRM1, PDGFRA, SETBP1, SETD2, SMAD4, and SPOP genes, with a mean F1 improvement of 9.4% (range 6–17%). The gene discussed is PBRM1; the disease is neoplasm.