–Secondary evolution to MDS–Critical drivers of clonal evolution are compensatory proliferation in the hypocellular marrow and immune escape (64)–Characteristic clonal findings: PNH clones with PIGA mutations, deletion of (antigenic) HLA alleles by loss of the chromosomal arm 6p or typical MDS mutations (ASXL1, DNMT3A, TET2, and others) (80–82). Here, PIGA is linked to myelodysplastic syndrome.