CDKN2A and gastrointestinal stromal tumor: Interestingly, the copy number profile of the primary tumor of patient #16, who was diagnosed with a low‐risk GIST and later developed metastatic disease, exhibited, in contrast to the other low‐risk GISTs, multiple chromosomal alterations, including loss of 1p, focal amplification of chromosome 6, and homozygous deletion of CDKN2A/B (Figure 3D).