This probe contains a 16q telomere internal control and is used for detecting 16q deletions in Wilms' tumor, which are associated with poor prognosis. Since the range of 16q deletions in Wilms' tumor is quite broad, our company has employed probes targeting the 16q22 and 16q23 loci, each paired with a 16q telomere internal control for detection. However, in a small number of cases, there is a possibility of deletion occurring only in the most distal chromosomal segment of 16q. Therefore, the D16S2621 probe was designed to be as close as possible to the chromosomal end, serving as an effective supplement to the F.01345 16q22/16q23 probe.