CDKN2A and neoplasm: CNV in the Cdkn2a/Cdkn2b tandem gene locus were small (maximum size range of 4–210 kb, S3 Fig) except for one tumour with an overlapping compound deletion, and one with a large amplification on chromosome 4 with the breakpoint within Cdkn2a. Deletions within the Ikzf1 and Pten loci were also small, ranging from less than 1 kb up to more than 200 kb, and included loss of proximal, terminal or internal regions of the genes, often with common breakpoint regions across multiple TL.