Fig. 1: Exome sequencing findings, trimethylated histone H3 interactions, and immunohistochemical staining.

(a) Schematic representation of the coding variants passing all filtering steps (with a genotype quality ≥90) that were found in the father (orange square), the mother (green circle), and the patient (blue circle) exomes. Manual curating by the integrative genomic viewer (IGV) excluded 4 of the 5 variants because they were either found in at least one of the progenitors or because they were probably the result of a sequencing artifact. The single de novo variant found (c.896A>T in DNMT3A) was confirmed by Sanger sequencing. (b) PyMOL representation of the interactions between the PWWP domain of DNMT3B and trimethylated K36 in histone H3 (structure deposited in the Protein Data Base with accession code 5CIU). The histone peptide is shown in yellow and the aromatic cage residues in blue. The represented residues are fully conserved in DNMT3A. The lysine residue 232 is equivalent to lysine 299 in DNMT3A and is represented in magenta. The dashed line depicts a hydrogen bond interaction between Lys232 and the carbonyl oxygen of a phenylalanine within the same loop. (c) Highly positive immunohistochemical staining for H3K9me3 in one representative c.896A>T DNMT3A-mutated tumor from the de novo patient (upper panel) compared to a DNMT3A wild-type tumor staining negative (lower panel). The scale bars represent 50 µm