There was not any difference in mitral valve leaflet lengths, or in indexed leaflet lengths, in phenotype negative MYBPC3-Q1061X mutation carriers and controls (25.4 vs 26.0 mm, P = 0.726 for AML and 11.2 vs 10.6 mm, P = 0.680 for PML, and 14.3 vs 14.5 mm, P = 0.881 for BSA-indexed AML and 6.1 vs 5.9 mm, P = 0.729 for BSA-indexed PML, respectively) in matched pairwise comparison. The gene discussed is PML; the disease is acute myeloid leukemia.