RAD21 and myelodysplastic syndrome: In FML034, the index case (II.2) was diagnosed with refractory anaemia with excess blasts (MDS-RAEB) at 51 years and harboured a single KDM6A variant (p.Ser1192Pro, absent in gnomAD; VAF = 50%, predicted pathogenic), while her mother (I.1), who also developed MDS in her 70’s, harboured six low-VAF secondary variants (ASXL1, CSF3R, GATA2, IKZF1 and two variants in RAD21; all with VAF < 10%) (Supplementary Table S3).