Heat map showing DNA copy number changes in a representative sample of 123 pediatric acute lymphoblastic leukemia (ALL) cases. The map was generated using dChipSNP and a Hidden Markov Model copy number inference algorithm. Each case is represented by a column and single nucleotide polymorphisms (SNPs) are arranged in rows by chromosomal location. Pink represents diploid copy number, light pink mono-allelic deletion, white bi-allelic deletion, and red amplification.