Distribution and features of A20 mutation in ABC DLBCL and MCL. (A) Schematic representation of human A20 with its functional domains. OTU is a deubiquitinating enzyme domain. A20 ZnF indicates the A20 zinc finger domain, which exerts E3 ligase activity. The location of A20 mutations is represented on the map with triangles. (B) Electrofluorograms showing partial nucleotide sequence of the A20 cDNA and genomic DNA (gDNA) of the patient sample and normal control. The splicing mutation in the patient results in exon 4 skipping and inclusion of whole intron 4 sequence. The intrallelic gene conversion in the patient disrupts a consensus sequence of acceptor splicing site of intron 3 (c.582_634 con c.434_486). Square in the sequence represents consensus sequence of splicing acceptor site. (C) Schematic representation of exon 4 skipping is shown. The location of gene conversions is represented on the map in triangles. The gene conversion may induce activation of cryptic splicing acceptor site of exon 4. Inclusion of whole intron 4 sequence in aberrantly spliced product adds 90 nucleotides followed by a stop codon (*).