Log₂ ratio SNP 500K copy number data (median smoothed with a window of 5 markers; blue is loss and red is gain). (A) Genomic copy number of chromosome 12p flanking ETV6 for 14 representative cases showing deletions at this locus at presentation (P) and relapse (R). (B) Copy number of chromosome 9p flanking CDKN2A/B. (C) Copy number of chromosome 6q. The chromosomal region of 6q16.2-3 which is recurrently deleted in pediatric ALL is indicated.