We performed Sanger sequencing of the PAX5 exons in a leukemia sample of the patient and performed SNP array-based copy number analysis on this sample, but did not observe a second alteration in PAX5. The only somatic aberration shared with the previously reported patients was a deletion in the CDKN2A/B locus, which was present in mosaic state in our patient (Supplementary Table 1). This evidence concerns the gene PAX5 and leukemia.