Zooming allows creation of small annotated regions on high-density profiles. Top: three regions of chromosome 2 from a high-density Affymetrix SNP6 array are shown along with some breakpoint annotations. There are almost 2 million probes on the array, 153663 probes on chromosome 2, and 2549 probes shown in these 3 windows. Bottom: zoom to show detail of windows 2 and 3. Annotations can be used to ensure that a smoothing model accurately recovers breakpoints around small ≈10kb alterations such as those shown in windows 2 and 3.