At the chromosome level, breakage-fusion-bridge (BFB) cycles are likely an underlying mechanism of ERBB2 amplification for at least a subset of breast tumors, as (a) the ERBB2 amplicons predominantly reside within a chromosome [61-65], and (b) copy-number loss at the telomeric side of the complex genomic regions (Figure 2) indicates chromosome breaks resulting in the loss of genetic materials. The gene discussed is ERBB2; the disease is breast neoplasm.