Mechanisms of MYD88 gene alteration. (A) Sanger sequence of MYD88 exon 5 in WM patient characterized with UPD on the 3p22 locus. The electrophoregram shows the recurrent homozygous L265P MYD88 mutation (arrow) detected in tumoral B cell of 1 patient. The reference sequence is reported in pink. (B) UPD (uniparental disomy, LOH without variation of copy number) of the short arm of chromosome 3 including MYD88 gene observed in 1 WM with MYD88 mutation using SNP array.